Pyrolysis Tar Upgrading

ABSTRACT

Processes and apparatus for preparing a liquid hydrocarbon product are provided. In one embodiment, a process for prepreparing a liquid hydrocarbon product includes thermally-treating a tar to produce a first tar composition and blending the tar composition with a utility fluid to form a tar-fluid mixture. The process includes separating the tar-fluid mixture to form a first lower-density portion and a first higher-density portion containing solids. The process further includes thermally-treating the first higher-density portion to form a thermally-treated first higher-density portion to convert at least a portion of the solids to liquid.

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 62/857,442, filed Jun. 5, 2019, and European PatentApplication No. 19206400.4 which was filed Oct. 31, 2019, which areincorporated herein by reference in their entireties.

FIELD

Embodiments generally relate to upgrading tar, such as by one or morethermal treatments. More particularly, embodiments relate to processesand apparatus for heat soaking steam cracked tar solids.

BACKGROUND

Hydrocarbon pyrolysis processes, such as steam cracking, crackhydrocarbon feedstocks into a wide range of relatively high valuemolecules, including ethylene, propene, butenes, steam cracked gas oil(“SCGO”), steam cracked naphtha (“SCN”), or any combination thereof.Besides these useful products, hydrocarbon pyrolysis can also produce asignificant amount of relatively low-value heavy products, such aspyrolysis tar. When the pyrolysis is produced by steam cracking, thepyrolysis tar is identified as steam-cracked tar (“SCT”). Economicviability of refining and petrochemical processes relies in part on theability to incorporate as much of the product and residual fractions,such as SCT, into the value chain. One use of residual fractions and/orrelatively low value products is to blend these fractions with otherhydrocarbons, e.g., with other feedstreams or products.

SCT, however, generally contains relatively high molecular weightmolecules, conventionally called Tar Heavies (“TH”), and an appreciableamount of sulfur. The presence of sulfur and TH make SCT a lessdesirable blendstock, e.g., for blending with fuel oil blend-stocks ordifferent SCTs. Compatibility is generally determined by visualinspection for solids formation, e.g., as described in U.S. Pat. No.5,871,634. Generally, SCTs have high viscosity and poor compatibilitywith other heavy hydrocarbons such as fuel oil, or are only compatiblein small amounts. Likewise, SCTs produced under specific conditionsgenerally have poor compatibility with SCT produced under differentconditions.

Viscosity and compatibility can be improved, and the amount of sulfurdecreased, by catalytically hydroprocessing the SCT. Catalytichydroprocessing of undiluted SCT, however, leads to appreciable catalystdeactivation and the formation of undesirable deposits (e.g., cokedeposits or particles) on the reactor internals. As the amount of thesedeposits increases, the yield of the desired upgraded pyrolysis tar(upgraded SCT) decreases and the yield of undesirable byproductsincreases. The hydroprocessing reactor pressure drop also increases, toa point where the reactor might be inoperable.

It is conventional to lessen deposit formation by hydroprocessing theSCT in the presence of a fluid, e.g., a solvent having significantaromatics content. The product of the hydroprocessing contains anupgraded SCT product that generally has a decreased viscosity, decreasedatmospheric boiling point range, and increased hydrogen content overthat of the feed's SCT, resulting in improved compatibility with fueloil blend-stocks. Additionally, hydroprocessing the SCT in the presenceof fluid produces fewer undesirable byproducts and the rate of increasein reactor pressure drop is lessened. Certain forms of SCT processingare disclosed in U.S. Pat. Nos. 2,382,260 and 5,158,668, and in U.S.Patent Application Publication No. US2008/0053869. P.C.T. PatentApplication Publications Nos. WO 2013/033590, WO 2018/111577, and WO2019.203981 disclose recycling a portion of the hydroprocessed tar foruse as the fluid.

The presence of solids in SCT represents a significant challenge toeffective SCT hydroprocessing. An appreciable amount of the SCT's solidsare in the form of particulates, e.g., coke (such as pyrolytic coke),oligomeric and/or polymeric material, inorganic solids (e.g., fines,metal, metal-containing compounds, ash, etc.) aggregates of one or moreof these, etc. Although removing SCT particulates, e.g., by filtration,settling, centrifuging, etc., results in an SCT that can be more readilyhydroprocessed, doing so undesirably decreases the yield ofhydroprocessed SCT. Moreover, managing a significant inventory ofremoved particulates can adversely affect process financials.

As an example, coke fines, inorganic fines, and other solids can bepresent in the SCT. Coke fines or particles can be or include pyrolyticcoke and/or polymeric coke. These fines or particles can be formedduring polymerization conditions (e.g., ≥150° C.) present in a primaryfractionator after pyrolysis tar formation (upstream of ahydroprocessor).

Thus, there is a need for improved tar conversion processes having fewersolids present in in hydrocarbon feedstocks to the tar conversion.

SUMMARY

In certain embodiments, processes are provided for upgrading tar, suchas pyrolysis tar. A tar, e.g., one comprising pyrolysis tar such assteam cracker tar, is subjected to a first thermal treatment to producea tar composition. At least a first higher-density portion and a firstlower-density portion are separated from the tar composition. The firsthigher-density portion is subjected to a second thermal treatment toproduce a thermally-treated first higher-density portion. A secondhigher-density portion and a second lower-density portion are separatedfrom the thermally-treated first higher-density portion. At least aportion of the second lower-density portion can be recycled to one ormore of (i) the tar, (ii) the tar composition, and (iii) the firsthigher-density portion. The second higher-density portion can beconducted away, e.g., for storage and/or further processing. It isobserved that the amount of solids in the thermally-treated firsthigher-density portion is less than that present in the firsthigher-density portion. Surprisingly, it is found that the secondthermal treatment is effective for converting solids in the firsthigher-density portion primarily to liquid in the thermally-treatedfirst higher-density portion, with little if any conversion tovapor-phase material. This in turn leads to improved process financials,greater efficiency, an increased amount of desired liquid-phasematerial, and a decreased amount of less-desired solids in comparisonwith conventional tar processing. Returning to the process at least aportion of the second lower-density portion (which contains liquidconverted from solids in the second thermal treatment) increases theamount of tar available for hydroprocessing, leading to an increasedyield in hydroprocessed tar.

In other embodiments, processes are provided for upgrading steam crackertar. A steam cracker feed is steam cracked to form a steam crackereffluent comprising steam cracker tar. A steam cracker tar compositionis produced by at least (i) separating at least a portion of the steamcracker tar from the steam cracker effluent and (ii) thermally-treatingat least a portion of the separated steam cracker tar in a first thermaltreatment. A tar-fluid mixture is produced by adding a first utilityfluid and/or a first separation fluid to the pyrolysis tar composition.A first separation is carried out in which (i) a first lower-densityportion comprising upgraded steam cracker tar and (ii) a firsthigher-density portion are separated from the thermally-treated steamcracker tar composition. At least a portion of the first lower-densityportion is conducted away, e.g., for hydroprocessing. Diluent, typicallycomprising a second utility fluid and/or second separation fluid, isintroduced into the first higher-density portion to form a diluted firsthigher-density portion. The diluted first higher-density portion issubjected to a second thermal treatment to produce a thermally-treatedfirst higher-density portion. The amount of solids in thethermally-treated first higher-density portion is less than that presentin the diluted first higher-density portion. In a second separation, asecond lower-density portion and a second higher-density portion areseparated from the thermally-treated first higher-density portion. Atleast a portion of the second lower-density portion is added to one ormore of (i) the steam cracker effluent, (ii) the steam cracker tar,(iii) the steam cracker tar composition; (iv) the tar-fluid mixture, (v)the first higher-density portion, and (vi) the first lower-densityportion.

In other embodiments, processes are provided for steam cracking a steamcracker feed comprising heavy oil, e.g., a heavy oil containing resid.The steam cracker effluent comprises steam cracker tar. The steamcracker includes a convection section and a radiant section. The radiantsection includes at least one radiant coil having an inlet and anoutlet. The steam cracker feed is preheated in the convection section. Aprimarily vapor-phase stream and a primarily non-vapor-phase stream areseparated from at least a portion of the preheated steam cracker feed,wherein ≥50 wt. % of resid in the feed is transferred to thenon-vapor-phase stream. At least a portion of the primarily vapor-phasestream is conducted into the radiant coil's inlet. Steam cracking iscarried out in the radiant coil in the presence of steam under steamcracking conditions. The steam cracking conditions include a temperatureat the radiant coil outlet in the range of from about 760° C. to about1200° C., a steam cracking pressure at the radiant coil outlet in therange of from about 1 bar (absolute) to about 10 bar (absolute), and asteam cracking residence time in the radiant coil in the range of fromabout 0.1 seconds to about 2 seconds. A steam cracker effluentcomprising steam cracker tar is conducted away from the radiant sectionvia the radiant coil outlet. At least a portion of the steam cracker taris separated from the steam cracker effluent. At least the separatedportion of the steam cracker tar is thermally-treated in a first thermaltreatment to produce a steam cracker tar composition. A first utilityfluid and/or first separation fluid is added to the steam cracker tarcomposition and/or to produce a tar-fluid mixture. At least twoadditional separations are carried out. In the first of theseseparations, at least one centrifuge can be used to separate from thetar-fluid mature (i) a first lower-density portion comprising upgradedsteam cracker tar and (ii) a first higher-density portion. At least aportion of the first lower-density portion is conducted away, e.g., forhydroprocessing. A diluent comprising a second utility fluid and/orsecond separation fluid is introduced into the first higher-densityportion to form a diluted first higher-density portion. The dilutedfirst higher-density portion is subjected to a second thermal treatmentto produce a thermally-treated first higher-density portion. The amountof solids in the thermally-treated first higher-density portion is lessthan that present in the diluted first higher-density portion. Thesecond of these separations, which can also utilize at least onecentrifuge, separates from the thermally-treated first higher-densityportion (i) a second lower-density portion and (ii) a secondhigher-density portion. At least a portion of the second lower-densityportion is added to one or more of (i) the steam cracker effluent, (ii)the steam cracker tar, (iii) the steam cracker tar composition, (iv) thetar-fluid mixture, (v) the first higher-density portion, and (vi) thefirst lower-density portion.

Other aspects of the invention include comminuting (e.g., by grinding)the first higher-density portion before the second thermal treatment.Still other aspects of the invention include separating the primarilyvapor-phase stream and the primarily non-vapor-phase stream from thepreheated steam cracker feed in a separation stage that is integratedwith the convection section. The separated primarily vapor-phase streamcan be exposed to additional heating in the convection section beforethe cracking in the radiant section.

Other aspects of the invention relate to systems and apparatus forcarrying out any of the forgoing processes, to the upgraded pyrolysistar, the upgraded steam cracker tar, and to compositions containing oneor more of these, to the separated lower-density and higher-densityportions, and to the use of any of these or any part thereof as a feedfor further processing, e.g., as a feed for tar hydroprocessing.

These and other features, aspects, and advantages of the processes willbecome better understood from the following description, appendedclaims, and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an apparatus for carrying out certainaspects of the present disclosure.

FIG. 2 is a graph illustrating the amount of solids loss (wt. %) as afunction of the temperature applied in a thermal treatment correspondingto the second thermal treatment, according to an embodiment.

DETAILED DESCRIPTION

The invention generally relates to separating a pyrolysis tar from apyrolysis effluent, and upgrading at least the separated pyrolysis tar.More particularly, the invention relates to separating at least aportion of the pyrolysis tar from the pyrolysis effluent, and exposingat least a portion of the separated pyrolysis tar to a first thermaltreatment to produce a pyrolysis tar composition. A first lower-densityportion (the upgraded pyrolysis tar) and a first higher-density portionare separated from the pyrolysis tar composition. At least a portion ofthe first higher-density portion is exposed to a second thermaltreatment to produce a thermally-treated first higher-density portionhaving fewer solids (weight basis) than does the first higher-densityportion. A second lower-density portion and second higher-densityportion are separated from the thermally-treated first higher-densityportion. At least a portion of the second lower-density portion can berecycled, e.g., to the separated pyrolysis tar and/or the pyrolysiseffluent. At least a portion of the second higher-density portion can beconducted away, e.g. for storage and/or further processing. It has beenfound that upgrading pyrolysis tar in this manner increases the amountof pyrolysis tar that can be made available for further upgrading, e.g.,in one or more hydroprocessing stages, and improves compatibility of theupgraded pyrolysis tar for blending with other hydrocarbon streams, andproduces fewer particulates compared with conventional processes. Theinvention will now be more particularly described with respect topyrolysis tar produced by steam cracking (steam cracker tar, or “SCT”).The invention is not limited to processing SCT, and this description isnot meant to foreclose upgrading of pyrolysis tar produced by otherforms of pyrolysis within the broader scope of the invention.

In certain aspects, the steam cracker effluent from the steam crackerfurnace is cooled, e.g., by an indirect heat transfer in one or moretransfer line exchangers. Alternatively or in addition, the steamcracker effluent and/or the cooled steam cracker effluent can bequenched (e.g., by a direct heat transfer). This can be carried out bycombining from the steam cracker effluent and/or the cooled steamcracker effluent with a quench oil. SCT is separated from the cooledand/or quenched steam cracker effluent in at least one separation stage.Certain processes for separating SCT from a steam cracker effluent andfor thermally-treating the separated SCT will now be described in moredetail. The invention is not limited to these aspects, and thisdescription should not be interpreted as foreclosing other processes forseparating and thermally-treating SCT within the broader scope of theinvention.

In certain aspects, SCT is separated from the cooled and/or quenchedsteam cracker effluent in a separation vessel, e.g., a tar knock-outdrum. The separated SCT accumulates in the bottom of the drum, andtypically combines with (i) material already present in the drum bottomsand (ii) optionally an added flux (e.g., utility fluid), to form an SCTcomposition. An overhead stream removed from the tar knock-out drum istypically conducted to at least one fractionator, e.g., a primaryfractionator. The overhead stream typically comprises (i) ≥75 wt. % ofwhat remains of the cooled and/or quenched steam cracker effluent afterSCT separation, e.g., ≥90 wt. %, such as ≥99 wt. %; (ii) ≥50 wt. % ofany flux as may be present in the tar knock-out drum, such as ≥75 wt. %,or ≥90 wt. %; and (iii) ≥50 wt. % of any quench oil (when used)conducted to the tar knock-out drum with quenched steam crackereffluent, e.g., ≥75 wt. %, such as ≥90 wt. %. Since the tar knock-outdrum in an imperfect separator, (i) the tar knock-out drum overheadstream can contain unseparated SCT, typically ≤10 wt. % of the totalamount of SCT in the steam cracker effluent, and (ii) the tar knock-outdrum bottoms comprises an SCT composition which includes the separated,thermally-treated SCT, ≥90 wt. % of any flux remaining after the tarknock-out drum overhead is conducted away, and ≥90 wt. % of any quenchoil remaining after the tar knock-out drum overhead is conducted away.In these and certain other aspects, the tar knock-out drum overhead isconducted to a primary fractionator, typically for separation from thetar knock-out drum overhead of a process gas stream comprising lightolefin, and optionally one or more of (i) a pyrolysis gasoline stream,(ii) a steam cracker gas oil stream, and (iii) a fractionator bottomsstream. The fractionator bottoms stream or portion thereof can beutilized as quench oil or a quench oil component. In these and certainother aspects, the specified SCT composition is produced by maintainingthe tar knock-out drum bottoms at a temperature in the specifiedtemperature range for a residence time in the specified residence timerange.

In other aspects, a tar knock-out drum is not used. In these and certainother aspects, the cooled and/or quenched steam cracker effluent isconducted directly from the effluent's cooling and/or quenching stagesto one or more fractionators, e.g., to a primary fractionator. Typicallyin these aspects the primary fractionator functions to separate from thecooled and/or quenched steam cracker effluent a process gas streamcomprising light olefin, and optionally one or more of (i) a pyrolysisgasoline stream, (ii) a steam cracker gas oil stream, (iii) a quench oilstream, and (iv) a bottoms stream comprising an SCT composition thatincludes separated SCT. In these and certain other aspects, thespecified thermally-treated SCT can be produced from the primaryfractionator bottoms stream. For example, a bottoms pump-around can beutilized, with the bottoms pump-around having one or more stages forheating and/or cooling via indirect heat transfer to achieve thespecified temperature range and specified residence time range for theSCT composition's thermal treatment.

In aspects which include a primary fractionator, fractionationconditions can be regulated to lessen or substantially ultimate theformation of solids (e.g., polymer) in the primary fractionator'sbottoms and/or quench oil streams. For example, the primary fractionatorinlet temperature can be preselected in the range of from 150° C. to300° C., e.g., 160° C. to 210° C. In conventional processes forupgrading SCT, solids produced in the first thermal treatment and/or inthe primary fractionator are conducted away as low-value stream, e.g.,from a filter and/or centrifuge. Surprisingly, it has been found that atleast a portion of these solids can be converted in the specified secondthermal treatment, with the conversion products being separated from theunconverted solids in the second SCT separation, recycled to thetar-fluid mixture, and then transferred in the first SCT separation tothe first lower-density portion. Doing so increases the amount ofmaterial in the higher-value first lower-density portion, which in turncan the amount of feed to beneficial processes such as SATC.

Certain aspects of the invention include separating at least a firsthigher-density portion and a first lower-density portion from the SCTcomposition. The separation can be carried out in one or more centrifugestages (collectively, a “first centrifuge”). Since the SCT compositiontypically exhibits a relatively large viscosity in the specifiedprocessing temperature ranges, a stream comprising a first utility fluidand/or a first separation fluid (these being of lesser viscosity thanthe SCT) is typically added upstream of at least this separation. Inthese cases, the first higher-density portion and the firstlower-density portion are separated from a tar-fluid mixture thatcomprises the SCT composition and the added utility fluid/separationfluid stream.

The first lower-density portion is typically subjected to additionalprocessing, e.g., in a solvent-assisted tar conversion (SATC) process.Conventional SATC processes are described, e.g., in P.C.T PatentApplication Publication No. WO2018/111577 and U.S. patent applicationsSer. Nos. 62/659,183 and 62/750,636, each of which is incorporatedherein by reference.

In conventional SATC, a first higher-density portion of the SCT can beconducted away from the process. Instead of doing so, certain aspects ofthe instant invention include subjecting this stream to furtherprocessing, e.g., one or more of (1) comminuting (such as grinding) thefirst higher-density portion, which achieve a reduction in the size ofsolids (e.g., particle size) to produce a comminuted firsthigher-density portion, (2) diluting the first higher-density portion,e.g., by adding before and/or after the comminuting one or more of (a) asecond utility fluid, (b) a second separation fluid, and (c) a recyclestream to produce a diluted first higher-density portion, and (3)thermally-treating the comminuted and/or diluted first higher-densityportion in a second thermal treatment to produce a thermally-treatedfirst higher-density portion. It has been discovered that diluting thefirst higher-density portion before the second thermal treatment canlessen or substantially prevent asphaltene-formation (oligomerization)reactions that might otherwise occur during the second thermaltreatment. It also has been found that the amount of solids in thethermally-treated first higher-density portion (weight basis, based onthe weight of the first higher-density portion) is less than the amountof solids in the first higher-density portion. This decrease in theamount of solids occurs whether or not comminuting is carried out beforethe second thermal treatment.

A second lower-density portion and a second higher-density portion areseparated from the thermally-treated first higher-density portion, e.g.,in one or more centrifuges (collectively “the “second centrifuge”). Thesecond higher-density portion can be sent away. At least a portion ofthe second lower-density portion can be returned (e.g. recycled) to theprocess. For example, certain aspects of the invention include adding atleast a portion of the second lower-density portion to one or more of(i) the steam cracker effluent, e.g., as quench oil, (ii) the SCT,before and/or during the first thermal treatment, (iii) the SCTcomposition, (iv) the tar-fluid mixture, before and/or during theseparation of the first higher-density portion and the firstlower-density portion, (v) the first higher-density portion, and (vi)the first lower-density portion. Recycling at least a portion of thesecond lower-density portion to one or more of streams (i) through (vi)results in a very desirable increase in the amount (by weight) of thefirst lower-density portion that is separated from the thermally-treatedSCT.

In certain aspects, at least a portion of the second lower-densityportion is recycled and combined with the SCT composition. Typically,the first utility fluid is also added to the SCT composition. Thecombination of SCT composition, the recycled portion of the secondlower-density portion, and the added first utility fluid if any(collectively in the form of the tar-fluid mixture) are conducted to aseparation stage for separation of the first lower-density portion andthe first higher-density portion. Doing so increases the weight ratio ofthe first lower-density portion: the first higher-density portion, andthus increases the amount of the first lower-density portion that isavailable for further processing, e.g., in a SATC process. This in turnincreases the amount of desirable hydroprocessed tar produced by SATC,as compared to conventional SCT conversion processes that do not use thesecond thermal treatment or the second centrifuging.

Processes and apparatus of the present disclosure provide the ability toupgrade an increased amount of SCT using downstream hydroprocessing, ascompared to conventional processes and apparatus for tar upgrading.Moreover, in aspects which utilize a tar knock-out drum upstream of aprimary fractionator, the primary fractionator bottoms section can bemaintained at a sufficiently low temperature to lessen the amount ofundesirable polymerization that may otherwise occur in a primaryfractionator's bottoms section operating at a greater temperature,e.g., >160° C.

Definitions

“Hydrocarbon-containing feed” refers to a flowable composition, e.g.,liquid phase, high viscosity, and/or slurry compositions, which (i)includes carbon bound to hydrogen and (ii) has a mass density greaterthan that of gasoline, typically ≥0.72 Kg/L, e.g., ≥0.8 Kg/L, such as≥0.9 Kg/L, or ≥1.0 Kg/L, or ≥1.1 Kg/L. Such compositions can include oneor more of crude oil, crude oil fraction, and compositions derivedtherefrom which (i) have a kinematic viscosity ≤1.5×10³ cSt at 50° C.,(ii) contain carbon bound to hydrogen, and (iii) have a mass density≥740 kg/m³. Hydrocarbon-containing feeds typically have a final boilingpoint at atmospheric pressure (“atmospheric boiling point”, or “normalboiling point”) ≥430° F. (220° C.). Certain hydrocarbon feeds includecomponents having an atmospheric boiling point ≥290° C., e.g.,hydrocarbon feeds containing ≥20% (by weight) of components having anatmospheric boiling point ≥290° C., e.g., ≥50%, such as ≥75%, or ≥90%.Certain hydrocarbon feeds appear to have the color black or dark brownwhen illuminated by sunlight, including those having a luminance ≤7cd/m², luminance being measured in accordance with CIECAM02, establishedby the Commission Internationale de l'eclairage. Non-limiting examplesof such feeds include pyrolysis tar, SCT, vacuum residual fracturing,atmospheric residual fracturing, vacuum gas oil (“VGO”), atmospheric gasoil (“AGO”), heavy atmospheric gas oil (“HAGO”), steam cracked gas oil(“SCGO”), deasphalted oil (“DAO”), cat cycle oil (“CCO”, including lightcat cycle oil, “LCCO”, and heavy cat cycle oil, “HCCO”), natural andsynthetic feeds derived from tar sands, or shale oil, coal.

The term “pyrolysis tar” means (a) a mixture of hydrocarbons having oneor more aromatic components and optionally (b) non-aromatic and/ornon-hydrocarbon molecules, the mixture being derived from hydrocarbonpyrolysis, with at least 70% of the mixture having a boiling point atatmospheric pressure that is ≥ about 550° F. (290° C.). Certainpyrolysis tars have an initial boiling point ≥200° C. For certainpyrolysis tars, ≥90.0 wt. % of the pyrolysis tar has a boiling point atatmospheric pressure ≥550° F. (290° C.). Pyrolysis tar can comprise,e.g., ≥50.0 wt. %, e.g., ≥75.0 wt. %, such as ≥90.0 wt. %, based on theweight of the pyrolysis tar, of hydrocarbon molecules (includingmixtures and aggregates thereof) having (i) one or more aromaticcomponents and (ii) a number of carbon atoms ≥ about 15. Pyrolysis targenerally has a metals content, ≤1.0×10³ ppmw, based on the weight ofthe pyrolysis tar, which is an amount of metals that is far less thanthat found in crude oil (or crude oil components) of the same averageviscosity.

“SCT” means pyrolysis tar obtained from steam cracking. Typically, SCTcomprises (a) a mixture of hydrocarbons having one or more aromaticcomponents and optionally (b) non-aromatic and/or non-hydrocarbonmolecules, the mixture having a 90% Total Boiling Point ≥550° F. (290°C.) (e.g., ≥90.0 wt. % of the SCT molecules have an atmospheric boilingpoint ≥550° F. (290° C.)). SCT can contain >50.0 wt. % (e.g., >75.0 wt.%, such as ≥90.0 wt. %), based on the weight of the SCT, of hydrocarbonmolecules (including mixtures and aggregates thereof) having (i) one ormore aromatic components and (ii) a number of carbon atoms ≥15. SCTgenerally has a metals content, ≤1.0×10³ ppmw, based on the weight ofthe SCT (e.g., an amount of metals that is far less than that found incrude oil (or crude oil components) of the same average viscosity). SCTtypically has a mass density ≥1.0 Kg/L, e.g., ≥1.05 Kg/L, such as ≥1.1Kg/L, or ≥1.15 Kg/L.

The invention is not limited to pyrolysis tars, such as SCT, and thisdescription should not be interpreted as foreclosing other tars orsimilar compositions within the broader scope of the invention. Forexample, in certain aspects the tar can be or include one or more tars,pitches, resids, gums, resins, and the like, such as those derived frompetroleum processes such as crude oil processing, resid processing,deasphalting, processing of atmospheric and/or vacuum tower bottoms,processing of compositions derived from catalytic cracking (e.g.,processing of main column bottoms), compositions derived fromhydroprocessing (e.g., processing of pitch obtained and/or derived fromcrude oil processing, resid processing including resid hydroprocessing,and the like) etc. Accordingly, the term “tar” encompasses thesecompositions and pyrolysis tars such as SCT.

“Solvent assisted tar conversion” or (“SATC”) is a process for producingan upgraded tar, such as SCT. The process includes hydroprocessing a tarstream in the presence of a utility fluid, and is generally described inP.C.T. Patent Application Publication No. WO 2018-111577. For example,SATC can include hydroprocessing one or more SCT streams, includingthose that have been subjected to prior pretreatments, in the presenceof a utility fluid, to produce a hydroprocessed tar having a lesserviscosity, improved blending characteristics, fewer heteroatomimpurities, and a lesser content of solids (e.g., fewer particles) ascompared to the SCT.

“Tar Heavies” (“TH”) means a product of hydrocarbon pyrolysis, typicallyincluded in a pyrolysis tar such as SCT. The TH typically have anatmospheric boiling point >565° C., and contain >5 wt. % of moleculeshaving a plurality of aromatic cores based on the weight of the tar. TheTH are typically solid at 25° C. and generally include the fraction ofSCT that is not soluble in a 5:1 (vol:vol) ratio of n-pentane: SCT at25° C. TH generally includes asphaltenes and other high molecular weightmolecules.

Tar can contain various forms of solids, where the term “solids”encompasses solid-phase materials and materials such as semi-solids,quasi-solids, and the like having some liquid-like characteristics andsome solid-like characteristics. The term “solids” also encompassesmaterial in the form of particles, meaning solids in particulate form.The term particles includes polymeric asphaltene particles, polymericcoke particles, pyrolytic coke particles, inorganic fines, other organicor inorganic particles, or any combination thereof. Particles present intar typically have a specific gravity from about 1.04 to about 1.5. Whena particulate content (whether by weight, volume, or number) of aflowable material, such as tar or upgraded tar, is compared with that ofanother flowable material, the comparison is made under substantiallythe same conditions, e.g., substantially the same temperature, pressure,etc. When samples of flowable materials are obtained from a process forcomparison elsewhere, e.g., in a laboratory, the particulate contentcomparison can be carried out under (i) conditions which simulate theprocess conditions and/or (ii) ambient conditions, e.g., a temperatureof 25° C. and a pressure of 1 bar (absolute).

Coke is a solid composition that can be found in certain tars, e.g.,pyrolysis tars such as SCT, “Pyrolytic coke” or “pyrolytic cokeparticles” means a material generated by pyrolysis of organic moleculespresent in SCT and/or quench oils. The pyrolytic coke is in solid form,e.g., particle form. “Polymeric coke” or “polymeric coke particles”means a material generated by oligomerization of olefinic molecules thatcan seed small foulant particles. The olefinic molecules can be presentin SCT and/or quench oils. The polymeric coke material or particlestypically have a specific gravity of about 1.04 to about 1.1, which ismuch less than the specific gravity of about 1.2 to about 1.3 for cokesolids (non-polymeric materials) typically found in tar.

“Solubility blending number (S)” and “insolubility number (I)” aredescribed in U.S. Pat. No. 5,871,634, incorporated herein by referencein its entirety, and determined using n-heptane as the so-called“nonpolar, nonsolvent” and chlorobenzene as the solvent. The S and Inumbers are determined at a weight ratio of oil to test liquid mixturein the range of from 1 to 5. Various such values are referred to herein.For example, “I_(TC)”” refers to the insolubility number of thepyrolysis tar composition, e.g., of an SCT composition; “I_(TF)” refersto the insolubility number of the tar-fluid mixture; “I_(LD)” refers tothe insolubility number of the first lower-density portion separatedfrom the tar-fluid mixture; “I_(FHD)” refers to the insolubility numberof the first higher-density portion, particularly the liquid-phase partthereof; “S_(Fluid)” refers to the solubility blending number of thefluid or the fluid-enriched stream, as appropriate. In conventionalnotation, these I and S values are frequently identified as I_(N) andS_(BN).

The terms “higher-density portion” and “lower-density portion” arerelative terms meaning that a higher-density portion has a mass density(ρ₂) that is higher than the density of the lower-density portion (ρ₁),e.g., ρ₂≥1.01*ρ₁, such as ρ₂≥1.05*ρ₁, or ρ₂≥1.10*ρ₁. In some aspects,the higher-density portion contains primarily solid components and thelower-density portion contains primarily liquid phase components. Thehigher-density component may also include liquid phase components thathave segregated from the lower-density portion. Likewise, thelower-density portion can contain solids (even in particulate form),e.g., those having a density similar to that of the pyrolysis tar'sliquid hydrocarbon component.

The term “portion” generally refers to one or more components derivedfrom a mixture, e.g., from the tar-fluid mixture.

Except for its use with respect to parts-per-million, the term “part” isused with respect to a designated process stream, generally indicatingthat less than the entire designated stream may be selected.

In this description, the particle size in a hydrocarbon can becharacterized by laser diffraction. It is noted that particle sizedistributions can vary between types of equipment when performing laserdiffraction for particle size characterization. Particle sizedistributions can be characterized using a Mastersizer from MalvernInstruments. If needed, the particle size distribution of a sample canbe determined according to a suitable ASTM method, such as ASTM D4464.

Pyrolysis and Pyrolysis Tar

Pyrolysis tar is a product or by-product of hydrocarbon pyrolysis, e.g.,steam cracking. Steam cracking will now be described in more detail. Thepresent disclosure is not limited to use of pyrolysis tars produced bysteam cracking, and this description is not meant to forecloseutilization of pyrolysis tar formed by other pyrolysis methods withinthe broader scope of the present disclosure.

Steam Cracking

A steam cracking plant typically comprises a furnace facility forproducing steam cracking effluent and a recovery facility for removingfrom the steam cracking effluent a plurality of products andby-products, e.g., light olefin and SCT. The furnace facility generallyincludes a plurality of steam cracking furnaces. Steam cracking furnacestypically include two main sections: a convection section and a radiantsection, the radiant section typically containing fired heaters. Fluegas from the fired heaters is conveyed out of the radiant section to theconvection section. The flue gas flows through the convection sectionand is then conducted away, e.g., to one or more treatments for removingcombustion by-products such as NON. A hydrocarbon-containing feed isintroduced into tubular coils (convection coils) located in theconvection section for pre-heating. Steam is added to the preheatedhydrocarbon-containing feed to produce a steam cracking feed (alsocalled steam cracker feed). The steam cracking feed is typicallyre-introduced into the convection section, e.g., via additionalconvection coils, to produce a heated steam cracking feed. Thecombination of indirect heating by the flue gas in the convectionsection and direct heating by the added steam leads may lead tovaporization, or to additional vaporization when the hydrocarbon feed isalready at least partially in the vapor phase when the hydrocarbon isfirst introduced into the convection section. Optionally, at least aportion of any heated steam cracking feed that is not in the vapor phaseis separated and conducted away. The heated steam cracking feed or avapor-phase component separated therefrom may be transferred from theconvection coils to one or more tubular radiant coils located in theradiant section. Indirect heating of the steam cracking feed in theradiant tubes results in cracking of at least a portion of the steamcracking feed's hydrocarbon component. Steam cracking conditions in theradiant section, can include, e.g., one or more of (i) a temperature inthe range of 760° C. to about 1200° C., such as from about 760° C. toabout 880° C., (ii) a pressure in the range of from 1 to 5 bars(absolute), or (iii) a cracking residence time in the range of from 0.10to 2 seconds.

In certain aspects, the hydrocarbon-containing feed comprises crude oilor a crude oil fraction, such as those comprising ≥1 wt. % ofhydrocarbons having a normal boiling point ≥566° C. (about 1050° F.)based on the weight of the hydrocarbon-containing feed, e.g., ≥5 wt. %,or ≥10 wt. %. In these aspects it is typically beneficial to utilize asteam cracking furnace that further comprises a vapor-liquid separationstage, e.g., a vapor-liquid separation drum that is thermally-integratedwith (but typically located external to) the steam cracking furnace'sconvection section.

When such a vapor-liquid separation stage is used, a primarilyvapor-phase stream and a primarily non-vapor-phase stream are separatedfrom the steam cracking feed in the vapor-liquid separation stage. Forexample, ≥50 wt. % of that portion of the crude oil (or crude oilfraction) having a normal boiling point ≥566° C. can be transferred tothe non-vapor-phase stream. The separated primarily vapor-phase streamis typically exposed to additional heating in the convection sectionbefore the cracking. For the primarily vapor-phase stream, ≥70 wt. %,such as ≥90 wt. % of the stream is in the vapor phase. For the primarilynon-vapor-phase stream, ≥70 wt. %, such as ≥90 wt. % of the stream isnot in the vapor phase.

At least a portion of the primarily vapor-phase stream is conducted intoan inlet of at least one radiant coil located in the radiant section forcracking under steam cracking conditions. The radiant coil includes aninlet and an outlet, and the steam cracking conditions include one ormore of: a temperature at the radiant coil outlet in the range of fromabout 760° C. to about 1200° C. (such as about 880° C. to about 1,200°C., such as about 1,000° C. to about 1,200° C.); a steam crackingpressure at the radiant coil outlet in the range of from about 1 bar(absolute) to about 10 bar (absolute) (such as about 1 bar (absolute) toabout 5 bar (absolute), alternatively about 6 bar (absolute) to about 10bars(absolute)); and/or a steam cracking residence time in the radiantcoil in the range of from about 0.1 seconds to about 2 seconds. A steamcracker effluent is conducted away from the radiant section for coolingand/or quenching. At least a portion of the SCT is separated from thecooled and/or quenched steam cracker effluent to produce the SCTcomposition.

Certain hydrocarbon-containing feeds will now be described in moredetail. The invention is not limited to these hydrocarbon-containingfeeds, and this description should not be interpreted as foreclosing thesteam cracking of other hydrocarbon-containing feeds within the broaderscope of the invention.

Although the hydrocarbon-containing feed can comprise one or more lighthydrocarbons such as methane, ethane, propane, butane etc., SCT yield isgreater when the hydrocarbon-containing feed includes a significantamount of higher molecular weight hydrocarbon. For example, thehydrocarbon-containing feed can comprise ≥1.0 wt. %, e.g., ≥10 wt. %,such as ≥25.0 wt. %, or ≥50.0 wt. % (based on the weight of thehydrocarbon-containing feed) of hydrocarbon compounds that are in theliquid and/or solid phase at 25° C. and a pressure of 1 bar absolute.

The hydrocarbon portion of the hydrocarbon-containing feed typicallycomprises ≥10.0 wt. %, e.g., ≥50.0 wt. %, such as ≥90.0 wt. % (based onthe weight of the hydrocarbon portion) of one or more of naphtha, gasoil, vacuum gas oil, waxy residues, atmospheric residues, residueadmixtures, crude oil and SCT. Certain hydrocarbon-containing feedscomprise ≥ about 0.1 wt. % asphaltenes. When the hydrocarbon-containingfeed includes crude oil and/or one or more fractions thereof, the crudeoil is optionally a desalted crude oil. Suitable crude oil include e.g.,high-sulfur virgin crude oils, such as those rich in polycyclicaromatics. A crude oil fraction can be produced by separatingatmospheric pipestill (“APS”) bottoms from a crude oil followed byvacuum pipestill (“VPS”) treatment of the APS bottoms. Suitable crudeoils include, For example, the hydrocarbon-containing feed can include≥90.0 wt. % of one or more crude oil fractions, such as those obtainedfrom an atmospheric APS and/or VPS; waxy residues; atmospheric residues;naphthas contaminated with crude; various residue admixtures.

The steam cracking feed is typically produced by heating thehydrocarbon-containing feed in one or more convection coils andcombining the heated hydrocarbon-containing feed with steam. Steamcracking feed typically comprises ≥10.0 wt. % hydrocarbon, based on theweight of the steam cracking feed, e.g., ≥25.0 wt. %, ≥50.0 wt. %, suchas ≥65 wt. %. Typically, ≥90 wt. % of the balance of the steam crackerfeed is steam.

In certain aspects, SCT is separated from the cooled and/or quenchedsteam cracker effluent in one or more separation stages. Conventionalseparation equipment can be used for separating SCT and other productsand by-products from the cooled and/or quenched steam cracking effluent,e.g., one or more flash drums, knock out drums, fractionators,water-quench towers, indirect condensers, etc. Suitable separationstages are described in U.S. Pat. No. 8,083,931, and in P.C.T. PatentApplication Publication No. WO 2018-111574, which are incorporated byreference herein in their entireties. SCT can be separated from thequenched effluent itself and/or from one or more streams that have beenseparated from the cooled and/or quenched effluent. For example, SCT canbe separated from a flash-drum bottoms (e.g., the bottoms of one or moretar knock out drums located downstream of the steam cracking furnace andupstream of the primary fractionator). Certain SCTs are a mixture ofprimary fractionator bottoms and tar knock-out drum bottoms.

Representative SCTs will now be described in more detail. Embodimentsare not limited to use of these SCTs, and this description is not meantto foreclose the processing of other SCTs, or of other pyrolysis tarswithin the broader scope of the present disclosure.

Steam Cracker Tar (“SCT”)

Typically, cooled and/or quenched steam cracker effluent includes steam,molecular hydrogen, hydrocarbon (saturated and unsaturated),non-hydrocarbon compositions, and solids (typically hydrocarbonaceoussolids, e.g., TH, and non-hydrocarbon solids) including particulates.For example, the cooled and/or quenched steam cracker effluent caninclude ≥1.0 wt. % of C₂ unsaturates and ≥0.1 wt. % of TH, the weightpercents being based on the weight of the cooled and/or quenched steamcracker effluent. It is also typical for the cooled and/or quenchedsteam cracker effluent to comprise ≥0.5 wt. % of TH, such as ≥1.0 wt. %TH. The SCT in the cooled and/or quenched steam cracker effluenttypically includes ≥50.0 wt. %, e.g., ≥75.0 wt. %, such as ≥90.0 wt. %of the total TH in the cooled and/or quenched steam cracker effluent.The TH are typically in the form of aggregates which include hydrogenand carbon and which have an average size in the range of 10.0 nm to300.0 nm in at least one dimension and an average number of carbon atoms≥50. Generally, the TH comprise ≥50.0 wt. %, e.g., ≥80.0 wt. %, such as≥90.0 wt. % of aggregates having a C:H atomic ratio in the range of from1.0 to 1.8, a molecular weight in the range of 250 to 5000, and amelting point in the range of 100° C. to 700° C. The SCT typicallyincludes ≥50.0 wt. %, e.g., ≥75.0 wt. %, such as ≥90.0 wt. % of thequenched effluent's TH, based on the total weight TH in the quenchedeffluent.

Representative SCTs typically have (i) a TH content in the range of from5.0 wt. % to 40.0 wt. %, based on the weight of the SCT, (ii) an APIgravity (measured at a temperature of 15.8° C.) of ≤8.5° API, such as≤8.0° API, or ≤7.5° API; and (iii) a 50° C. viscosity in the range of200 cSt to 1.0×10⁷ cSt, e.g., 1×10³ cSt to 1.0×10⁷ cSt, as determined byA.S.T.M. D445. The SCT can have, e.g., a sulfur content that is >0.5 wt.%, or >1 wt. %, or more, e.g., in the range of 0.5 wt. % to 7.0 wt. %,based on the weight of the SCT. In aspects where steam cracking feeddoes not contain an appreciable amount of sulfur, the SCT can comprise≤0.5 wt. % sulfur, e.g., ≤0.1 wt. %, such as ≤0.05 wt. % sulfur, basedon the weight of the SCT.

The SCT can have, e.g., (i) a TH content in the range of from 5.0 wt. %to 40.0 wt. %, based on the weight of the SCT; (ii) a density at 15° C.in the range of 1.01 g/cm³ to 1.19 g/cm³, e.g., in the range of 1.07g/cm³ to 1.18 g/cm³; and (iii) a 50° C. viscosity ≥200 cSt, e.g., ≥600cSt, or in the range of from 200 cSt to 1.0×10⁷ cSt. The specifiedhydroprocessing is particularly advantageous for SCTs having 15° C.density that is ≥1.10 g/cm³, e.g., ≥1.12 g/cm³, ≥1.14 g/cm³, ≥1.16g/cm³, or ≥1.17 g/cm³. Optionally, the SCT has a 50° C. kinematicviscosity ≥1.0×10⁴ cSt, such as ≥1.0×10⁵ cSt, or ≥1.0×10⁶ cSt, or even≥1.0×10⁷ cSt. Optionally, the SCT has an I_(N)≥80 and ≥70 wt. % of thepyrolysis tar's molecules have an atmospheric boiling point of ≥290° C.Typically, the SCT has an insoluble content (“IC_(T)”) ≥0.5 wt. %, e.g.,≥1 wt. %, such as ≥2 wt. %, or ≥4 wt. %, or ≥5 wt. %, or ≥10 wt. %.

In at least one embodiment, the SCT includes a mixture of hydrocarbonshaving one or more aromatic components and optionally non-aromaticsand/or non-hydrocarbons, with at least 70% of the mixture having aboiling point at atmospheric pressure that is about 550° F. (290° C.) ormore. The SCT typically comprises hydrocarbon (including mixtures andaggregates thereof) having (i) one or more aromatic components and (ii)a number of carbon atoms greater than about 15. The SCT generally has ametals content of 1000 ppmw or less, based on the weight of thepyrolysis tar, which is an amount of metals that is far less than thatfound in crude oil (or crude oil components) of the same averageviscosity. Optionally, the SCT has a normal boiling point ≥290° C., aviscosity at 15° C. ≥1×10⁴ cSt, and a density ≥1.1 g/cm³. The SCT can bea mixture which includes a first SCT and one or more additionalpyrolysis tars, e.g., a combination of the first SCT and one or moreadditional SCTs. When the SCT is a mixture, it is typical for at least70 wt. % of the mixture to have a normal boiling point of at least 290°C., and include olefinic hydrocarbon which contribute to the tar'sreactivity under hydroprocessing conditions. When the mixture comprisesfirst and second pyrolysis tars (one or more of which is optionally anSCT) ≥90 wt. % of the second pyrolysis tar optionally has a normalboiling point ≥290° C.

It has been found that an increase in reactor fouling occurs duringhydroprocessing of a tar-fluid mixture comprising an SCT having anexcessive amount of olefinic hydrocarbon. In order to lessen the amountof reactor fouling, it is beneficial for the SCT to have an olefincontent of ≤10.0 wt. % (based on the weight of the SCT), e.g., ≤5.0 wt.%, such as ≤2.0 wt. %. More particularly, it has been observed that lessreactor fouling occurs during the hydroprocessing when the SCT has (i)an amount of vinyl aromatics of ≤5.0 wt. % (based on the weight of theSCT), e.g., ≤3 wt. %, such as ≤2.0 wt. % and/or (ii) an amount ofaggregates which incorporate vinyl aromatics of ≤5.0 wt. % (based on theweight of the SCT), e.g., ≤3 wt. %, such as ≤2.0 wt. %.

The SCT Composition

The SCT composition generally comprises ≥40 wt. % of SCT that has beenseparated from the steam cracker effluent, based on the weight of theSCT composition, e.g., ≥60 wt. %, such as ≥70 wt. %, or more. The SCTcomposition may further comprise compositions formed during thermaltreatment of the SCT. In certain aspects, e.g., aspects where (i) quenchoil is not used to quench the steam cracker effluent and (ii) utilityfluid is not added to the tar knock-out drum, the SCT composition cancomprise ≥90 wt. % of thermally-treated SCT, e.g., ≥95 wt. %, or ≥99 wt.%, or more. The SCT composition typically comprises ≥90.0 wt. % SCT thathas been (i) separated from the cooled and/or quenched steam crackereffluent, and (ii) thermally-treated. SCT may father include materialderived SCT that has been recycled to the first thermal treatment or alocation upstream thereof (e.g., a recycled portion of the secondlower-density portion. An SCT composition obtained from one or more ofthe specified SCT sources may contain ≥50.0 wt. % of SCT, based on theweight of the stream, e.g., ≥75.0 wt. %, such as ≥90.0 wt. %, or more.In aspects where ≥50 wt. %, or ≥75 wt. %, or ≥90 wt. %, or more of theSCT in the SCT composition is SCT separated in a tar knock-out drum,more than 90 wt. % of the remainder of the SCT stream's weight (e.g.,the part of the stream that is not SCT, if any) typically comprises oneor more of (i) any flux (e.g., utility fluid) remaining with the SCTafter the tar knock-out drum overhead is conducted away, in aspectswhere flux is added to the tar knock-out drum; (ii) any quench oil asmay remain with the SCT after the tar knock-out drum overhead isconducted away, in aspects where a quench oil is introduced into thesteam cracker effluent and/or the cooled steam cracker effluent; (iii)material formed during or as a result of the first thermal treatment;and (iv) particulates.

Aspects in which the first thermal treatment includes heat soaking in atar knock out drum will now be described in more detail. The inventionis not limited to these aspects, and this description should not beinterpreted as foreclosing (i) other forms of thermal treatment, such asa thermal treatment of an SCT composition in a primary fractionator, or(ii) thermal treatments of other forms of pyrolysis tar.

Thermal Treatment of the SCT by Heat Soaking

During heat soaking, at least the separated SCT is maintained in a heatsoaking location, e.g., in a bottoms region of the tar knock-out drum,or in one or more soaker vessels adapted to this purpose and locatedexternal to the tar knock-out drum. Conventional equipment for heatsoaking SCT can be used, but the invention is not limited thereto.Conventional equipment configuration for heat soaking SCT is disclosedin P.C.T. Patent Application Publication No. WO 2018-111574, whichdiscloses heat soaking an SCT in a bottoms region of a tar knock-outdrum and optionally in the presence of utility fluid added as a flux.Flux may be used as an aid in the separation and heat soaking, e.g., aflux having substantially the same composition as the first utilityfluid. The separating and heat soaking of the SCT can be carried outbefore, during, and/or after adding the flux. Since aspects of theinvention include at least one additional thermal treatment of a streamderived from the SCT composition (the second thermal treatment), thethermal treatment of the separated SCT is called a “first thermaltreatment” or “first heat soak”.

Using, e.g., the heat soaking configuration disclosed in P.C.T. PatentApplication Publication No. WO 2018-111574, at least the separated SCTcan independently be heated and/or cooled to achieve a desired heat soaktemperature (T_(HS1)) and for a desired period of time (t_(HS1)).Temperature T_(HS1) is typically in a range of about 200° C., about 220°C., about 230° C., about 240° C., about 250° C., about 260° C., about270° C., about 275° C., about 280° C., or about 290° C. to about 295°C., about 300° C., about 310° C., about 320° C., about 325° C., about330° C., about 340° C., about 350° C., about 360° C., about 375° C.,about 400° C., about 450° C., about 500° C., or higher. For example,T_(HS1) can be in a range of about 200° C. to about 500° C., about 230°C. to about 500° C., about 250° C. to about 500° C., about 280° C. toabout 500° C., about 290° C. to about 500° C., about 300° C. to about500° C., about 320° C. to about 500° C., about 350° C. to about 500° C.,about 250° C. to about 450° C., about 280° C. to about 450° C., about290° C. to about 450° C., about 300° C. to about 450° C., about 320° C.to about 450° C., about 350° C. to about 450° C., about 250° C. to about400° C., about 280° C. to about 400° C., about 290° C. to about 400° C.,about 300° C. to about 400° C., about 320° C. to about 400° C., about350° C. to about 400° C., about 250° C. to about 350° C., about 280° C.to about 350° C., about 290° C. to about 350° C., about 300° C. to about350° C., about 320° C. to about 350° C., or about 330° C. to about 350°C. Although it is not required to maintain the separated SCT at asubstantially-constant temperature during the heat soak (i.e., asubstantially constant temperature within the specified range ofT_(HS1)), it is typical to do so.

The first heat soaking is typically carried out for a predetermined timet_(HS1) in a range of about 2 min, about 5 min, about 10 min, about 12min, or about 15 min to about 20 min, about 25 min, about 30 min, about45 min, about 60 min, about 90 min, about 2 hr, about 3 hr, about 5 hr,or longer. For example, t_(HS1) can be in a range of about 5 min toabout 5 hr, about 5 min to about 3 hr, about 5 min to about 2 hr, about5 min to about 1 hr, about 5 min to about 45 min, about 5 min to about30 min, or about 5 min to about 20 min. In one or more examples, t_(HS1)is in a range of about 2 min, about 5 min, about 10 min, about 15 min,or about 20 min to about 30 min, about 45 min, about 60 min, about 90min, about 2 hr, about 3 hr, or about 5 hr to dissolve and/or decomposeat least a portion of particles present in the separated SCT.

While not wishing to be bound by any theory or model, it is believedthat the first heat soaking dissolves and/or decomposes particles in theseparated SCT, or otherwise reduces particle content. It is alsoobserved that after maintaining the separated SCT at temperature T_(HS1)for the predetermined time t_(HS1), the SCT composition typicallycontains fewer particles than the separated SCT. In one or moreembodiments, about 25 wt. %, about 30 wt. %, about 35 wt. %, or about 40wt. % to about 45 wt. %, about 50 wt. %, about 60 wt. %, about 70 wt. %,about 75 wt. %, about 80 wt. %, about 85 wt. %, about 90 wt. %, about 92wt. %, about 95 wt. %, about 97 wt. %, about 98 wt. %, about 99 wt. %,or more of the particles in the separated SCT are dissolved and/ordecomposed during and/or as a result of the first heat soak. In someexamples, at least 25 wt. %, at least 30 wt. %, at least 35 wt. %, atleast 40 wt. %, at least 45 wt. %, at least 50 wt. %, at least 60 wt. %,at least 70 wt. %, at least 75 wt. %, at least 80 wt. % to about 85 wt.%, about 90 wt. %, about 92 wt. %, about 95 wt. %, about 97 wt. %, about98 wt. %, about 99 wt. %, or more of the particles in the separated SCTare dissolved and/or decomposed during and/or as a result of the firstheat soak. For example, about 25 wt. % to about 99 wt. %, about 30 wt. %to about 99 wt. %, about 35 wt. % to about 99 wt. %, about 40 wt. % toabout 99 wt. %, about 45 wt. % to about 99 wt. %, about 50 wt. % toabout 99 wt. %, about 60 wt. % to about 99 wt. %, about 70 wt. % toabout 99 wt. %, about 75 wt. % to about 99 wt. %, about 25 wt. % toabout 95 wt. %, about 30 wt. % to about 95 wt. %, about 35 wt. % toabout 95 wt. %, about 40 wt. % to about 95 wt. %, about 45 wt. % toabout 95 wt. %, about 50 wt. % to about 95 wt. %, about 60 wt. % toabout 95 wt. %, about 70 wt. % to about 95 wt. %, about 75 wt. % toabout 95 wt. %, about 25 wt. % to about 90 wt. %, about 30 wt. % toabout 90 wt. %, about 35 wt. % to about 90 wt. %, about 40 wt. % toabout 90 wt. %, about 45 wt. % to about 90 wt. %, about 50 wt. % toabout 90 wt. %, about 60 wt. % to about 90 wt. %, about 70 wt. % toabout 90 wt. %, about 75 wt. % to about 90 wt. %, about 25 wt. % toabout 80 wt. %, about 30 wt. % to about 80 wt. %, about 35 wt. % toabout 80 wt. %, about 40 wt. % to about 80 wt. %, about 45 wt. % toabout 80 wt. %, about 50 wt. % to about 80 wt. %, about 60 wt. % toabout 80 wt. %, about 70 wt. % to about 80 wt. %, or about 75 wt. % toabout 80 wt. % of the particles in the separated SCT are dissolvedand/or decomposed during and/or as a result of the first heat soak.

The SCT composition typically comprises separated SCT that is nowthermally-treated, plus any added flux, minus that portion of theseparated SCT as may convert during or as a result of the first thermaltreatment, plus at least a portion of certain conversion products as mayform during or as a result of the first thermal treatment (e.g., solids,such as polymeric particulate). Other examples of the latter categoryinclude certain compositions (e.g., those having a normal boiling pointrange similar to that of SCT) as might result from decomposition duringthe first thermal treatment of any solids present in the separated SCT.Certain solids, e.g., particulate solids, have been found to form duringand/or as a result of the first thermal treatment, e.g., bypolymerization of separated SCT in a tar knock-out drum and/or primaryfractionator.

The SCT composition is subjected to further processing, includingseparating a first higher-density portion and a first lower-densityportion in a first stage of SCT separation (the “first SCT separationstage”). At least a portion of any solids formed during and/or as aresult of the first thermal treatment typically reside in the firsthigher-density portion.

Although the SCT composition can be the feed to the first SCT separationstage, it is typical to combine the SCT composition with a recycledportion of the second lower-density portion to form a tar-fluid mixtureupstream of the first SCT separation stage. Certain representativetar-fluid mixtures will now be described in more detail. The inventionis not limited to these tar-fluid mixtures, and this description shouldnot be interpreted as excluding other tar-fluid mixtures within thebroader scope of the invention.

The Tar-Fluid Mixture

The tar-fluid mixture typically comprises the SCT composition and fluid.The fluid comprises a recycled portion of the second lower-densityportion, and typically further comprises the first utility fluid and/orthe first separation fluid. The amount (e.g., by weight) of fluid in thetar-fluid mixture is typically in the range of from 20 wt. % to 60 wt.%, e.g., 30 wt. % to 50 wt. %. The amount (e.g., by weight) of therecycled portion of the second lower-density portion in the fluid istypically substantially equal to the weight of material (typicallyparticles) converted to lesser density during or as a result of thesecond thermal treatment (e.g., using FIG. 2), plus the weight ofdiluent (e.g., second utility fluid and/or second separation fluid)added to the first higher-density portion, comminuted firsthigher-density portion, diluted first higher-density portion, and/orthermally-treated first higher-density portion. Typically ≥50 wt. % ofthe remainder of the fluid (e.g., the part of the fluid that is notrecycled second lower-density portion) is the first utility fluid and/orfirst separation fluid, e.g., ≥75 wt. %, such as ≥90 wt. %, or ≥99 wt.%. The first utility fluid (and/or first separation fluid) when used maybe added to (i) the SCT composition (which may already contain at leastsome of the utility fluid as flux) and/or (ii) to a mixture of the SCTcomposition and the recycled portion of the second lower-densityportion. In other words, the first utility fluid and/or the firstseparation fluid can be added to the SCT composition before, during,and/or after the combining of the SCT composition with the recycledportion of the second lower-density portion. The tar-fluid mixture has alesser viscosity than does the SCT composition.

The tar-fluid mixture generally contains ≥5 wt. % of the SCTcomposition, e.g., ≥10 wt. %, ≥20 wt. %, ≥30 wt. %, ≥40 wt. %, ≥50 wt.%, ≥60 wt. %, ≥70 wt. %, ≥80 wt. %, or ≥90 wt. % SCT composition, basedon the total weight of the tar-fluid mixture (e.g., a combined weight ofall of the components of the tar-fluid mixture). Additionally oralternatively, the tar-fluid mixture may include ≤10 wt. % of the SCTcomposition, e.g., ≤20 wt. %, ≤30 wt. %, ≤40 wt. %, ≤50 wt. %, ≤60 wt.%, ≤70 wt. %, ≤80 wt. %, ≤90 wt. %, or ≤95 wt. % of the SCT composition,based on the total weight of the tar-fluid mixture. Ranges expresslydisclosed include combinations of any of the above-enumerated values,e.g., about 5 wt. % to about 95 wt. %, about 5 wt. % to about 90 wt. %,about 5 wt. % to about 80 wt. %, about 5 wt. % to about 70 wt. %, about5 wt. % to about 60 wt. %, about 5 wt. % to about 50 wt. %, about 5 wt.% to about 40 wt. %, about 5 wt. % to about 30 wt. %, about 5 wt. % toabout 20 wt. %, or about 5 wt. % to about 10 wt. % of the SCTcomposition.

In addition to the SCT composition, the tar-fluid mixture typicallyfurther comprises ≥5 wt. % of utility fluid, e.g., ≥10 wt. %, ≥20 wt. %,≥30 wt. %, ≥40 wt. %, ≥50 wt. %, ≥60 wt. %, ≥70 wt. %, ≥80 wt. %, or ≥90wt. %, based on the total weight of the tar-fluid mixture (e.g., acombined weight of all of the components of the tar-fluid mixture).Additionally or alternatively, the tar-fluid mixture may include ≤10 wt.% of utility fluid, e.g., ≤20 wt. %, ≤30 wt. %, ≤40 wt. %, ≤50 wt. %,≤60 wt. %, ≤70 wt. %, ≤80 wt. %, ≤90 wt. %, or ≤95 wt. % utility fluid,based on the total weight of the tar-fluid mixture. Ranges expresslydisclosed include combinations of any of the above-enumerated values,e.g., about 5 wt. % to about 95 wt. %, about 5 wt. % to about 90 wt. %,about 5 wt. % to about 80 wt. %, about 5 wt. % to about 70 wt. %, about5 wt. % to about 60 wt. %, about 5 wt. % to about 50 wt. %, about 5 wt.% to about 40 wt. %, about 5 wt. % to about 30 wt. %, about 5 wt. % toabout 20 wt. %, or about 5 wt. % to about 10 wt. % utility fluid.

In certain aspects, the tar-fluid mixture includes (i) the SCTcomposition, (ii) the recycled portion of the second lower-densityportion, and (iii) any first utility fluid added to the SCT compositionbefore the first SCT separation stage. For example, the tar-fluidmixture can contain about 15 wt. %, about 20 wt. %, about 25 wt. %, 30wt. %, about 35 wt. %, about 40 wt. %, about 45 wt. %, or about 50 wt. %to about 55 wt. %, about 60 wt. %, about 65 wt. %, about 70 wt. %, about75 wt. %, about 80 wt. %, about 85 wt. %, or about 90 wt. %, or more ofthe utility fluid, based on a combined weight of the tar-fluid mixture(e.g., a combined weight of all of the components of the tar-fluidmixture). Typically, the tar-fluid mixture contains about 15 wt. % toabout 90 wt. %, about 20 wt. % to about 90 wt. %, about 20 wt. % toabout 80 wt. %, about 20 wt. % to about 70 wt. %, about 20 wt. % toabout 60 wt. %, about 20 wt. % to about 50 wt. %, about 20 wt. % toabout 50 wt. %, about 20 wt. % to about 40 wt. %, about 20 wt. % toabout 30 wt. %, about 25 wt. % to about 90 wt. %, about 30 wt. % toabout 85 wt. %, about 30 wt. % to about 80 wt. %, about 35 wt. % toabout 80 wt. %, about 40 wt. % to about 80 wt. %, about 40 wt. % toabout 75 wt. %, about 40 wt. % to about 70 wt. %, about 40 wt. % toabout 65 wt. %, about 40 wt. % to about 60 wt. %, about 40 wt. % toabout 55 wt. %, about 40 wt. % to about 50 wt. %, about 40 wt. % toabout 45 wt. %, about 45 wt. % to about 80 wt. %, about 45 wt. % toabout 75 wt. %, about 45 wt. % to about 70 wt. %, about 45 wt. % toabout 65 wt. %, about 45 wt. % to about 60 wt. %, about 45 wt. % toabout 55 wt. %, about 45 wt. % to about 50 wt. %, about 50 wt. % toabout 80 wt. %, about 50 wt. % to about 75 wt. %, about 50 wt. % toabout 70 wt. %, about 50 wt. % to about 65 wt. %, about 50 wt. % toabout 60 wt. %, about 50 wt. % to about 55 wt. %, about 55 wt. % toabout 80 wt. %, about 55 wt. % to about 75 wt. %, about 55 wt. % toabout 70 wt. %, about 55 wt. % to about 65 wt. %, or about 55 wt. % toabout 60 wt. % of the utility fluid, based on the total weight of thetar-fluid mixture.

The combining of the SCT composition, the utility fluid, and therecycled portion of the second lower-density portion is carried outunder conditions which lessen or substantially prevent asphalteneprecipitation. Those skilled in the art will appreciate that in doing soone can make use of blend information for these compositions, such asinsolubility number I_(TF) and solubility blending number S_(TF).Accordingly, in some aspects, the tar-fluid mixture has an S_(TF)≤150,such as ≤140, or ≤130, or ≤120, or ≤115, or ≥110, or ≥105, or ≥100, or≥95, or ≥90. In some examples, the tar-fluid mixture has an S_(TF) ofabout 70, about 80, about 85, about 90, about 95, about 100, about 105,about 110, about 115, about 120, about 130, about 140, or about 150. Forexample, the tar-fluid mixture can have an S_(TF) in a range of about 70to about 150, about 70 to about 130, about 70 to about 125, about 70 toabout 120, about 70 to about 115, about 70 to about 110, about 70 toabout 105, about 70 to about 100, about 70 to about 95, about 70 toabout 90, about 70 to about 85, about 80 to about 130, about 80 to about125, about 80 to about 120, about 80 to about 115, about 80 to about110, about 80 to about 105, about 80 to about 100, about 80 to about 95,about 80 to about 90, about 85 to about 130, about 85 to about 125,about 85 to about 120, about 85 to about 115, about 85 to about 110,about 85 to about 105, about 85 to about 100, about 85 to about 95,about 85 to about 90, about 90 to about 130, about 90 to about 125,about 90 to about 120, about 90 to about 115, about 90 to about 110,about 90 to about 105, about 90 to about 100, or about 90 to about 95.

Particularly in aspects where tar-fluid mixture components are notsubjected to subsequent hydroprocessing, the fluid of the tar-fluidmixture may further comprise a first separation fluid, with “fluid” inthis sense meaning the total amount of first utility fluid in thetar-fluid mixture plus the total amount of first separation fluid in thetar-fluid mixture. Separation fluids may be used as an aid in separatingthe first higher-density and lower-density portion and in separating thesecond higher-density and lower-density portions. Although theseparation fluid can have substantially the same composition as that ofthe utility fluid, it is typically of different composition. Thetar-fluid mixture may optionally include a first separation fluid,typically in an amount of ≤35 wt. %, e.g., ≤30 wt. %, ≤25 wt. %, ≤20 wt.%, ≤15 wt. %, ≤10 wt. %, ≤5 wt. %, ≤2.5 wt. %, or ≤1.5 wt. %, based onthe total weight of fluid (e.g., utility fluid plus separation fluid) inthe tar-fluid mixture. Additionally or alternatively, the separationfluid may be present in an amount ≥ to 0 wt. %, e.g., ≥1.5 wt. %, ≥2.5wt. %, ≥5 wt. %, ≥10 wt. %, ≥15 wt. %, ≥20 wt. %, ≥25 wt. %, or ≥30 wt.%, based on the total weight of the fluid in the tar-fluid mixture.Ranges include combinations of any of the above-enumerated values, e.g.,0 to about 35 wt. %, 0 to about 30 wt. %, 0 to about 25 wt. %, 0 toabout 20 wt. %, 0 to about 15 wt. %, 0 to about 10 wt. %, 0 to about 5wt. %, 0 to about 2.5 wt. %, 0 to about 1.5 wt. % separation fluid,based on the total weight of fluid in the tar-fluid mixture.

Thus, in some aspects, the fluid comprises ≥50 wt. % of the separationfluid, e.g., ≥60 wt. %, ≥70 wt. %, ≥80 wt. %, ≥90 wt. %, ≥95 wt. %,≥97.5 wt. %, ≥99 wt. %, or about 100 wt. % separation fluid, based onthe total weight of the tar-fluid mixture. Additionally oralternatively, the tar-fluid mixture may include ≤99 wt. % of theseparation fluid, e.g., ≤97.5 wt. %, ≤95 wt. %, ≤90 wt. %, ≤80 wt. %,≤70 wt. %, or ≤60 wt. % separation fluid, based on the total weight ofthe tar-fluid mixture. Ranges expressly disclosed include combinationsof any of the above-enumerated values, e.g., about 50 wt. % to about 100wt. %, about 60 wt. % to about 100 wt. %, about 70 wt. % to about 100wt. %, about 80 wt. % to about 100 wt. %, about 90 wt. % to about 100wt. %, about 95 wt. % to about 100 wt. %, about 97.5 wt. % to about 100wt. %, or about 99 wt. % to about 100 wt. % of the separation fluid.

The dynamic viscosity of the tar-fluid mixture is typically less thanthat of the SCT composition. In some aspects, the dynamic viscosity ofthe tar-fluid mixture may be ≥0.5 cPoise, e.g., ≥1 cPoise, ≥2.5 cPoise,≥5 cPoise, ≥7.5 cPoise, at a temperature of about 50° C. to about 250°C., such as about 100° C. Additionally or alternatively, the dynamicviscosity of the tar-fluid mixture may be ≤10 cPoise, e.g., ≤7.5 cPoise,≤5 cPoise, ≤2.5 cPoise, ≤1 cPoise, ≤0.75 cPoise, at a temperature ofabout 50° C. to about 250° C., such as about 100° C. Ranges can includecombinations of any of the above-enumerated values, e.g., about 0.5cPoise to about 10 cPoise, about 1 cPoise to about 10 cPoise, about 2.5cPoise to about 10 cPoise, about 5 cPoise to about 10 cPoise, or about7.5 cPoise to about 10 cPoise, at a temperature of about 50° C. to about250° C., such as about 100° C.

Utility Fluids

The first and second utility fluids can be selected independently. Eachcan be selected from among conventional utility fluids, such as thoseused as a process aid for hydroprocessing tar such as SCT, but theinvention is not limited thereto. Suitable utility fluids include thosedisclosed in U.S. Provisional Patent Application No. 62/716,754; U.S.Pat. Nos. 9,090,836; 9,637,694; and 9,777,227; and 9,809,756; thesebeing incorporated by reference herein in their entireties, and inP.C.T. Patent Application Publication No. WO 2018-111574. Although it isnot required, the first and second utility fluids can have substantiallythe same composition and can be referred to as “utility fluid”.

The utility fluid typically comprises ≥40 wt. %, of at least onearomatic or non-aromatic ring-containing compound, e.g., ≥45 wt. %, ≥50wt. %, ≥55 wt. %, or ≥60 wt. %, based on the weight of the utilityfluid. Particular utility fluids contain ≥40 wt. %, ≥45 wt. %, ≥50 wt.%, ≥55 wt. %, or ≥60 wt. % of at least one multi-ring compound, based onthe weight of the utility fluid. The compounds contain a majority ofcarbon and hydrogen atoms, but can also contain a variety ofsubstituents and/or heteroatoms.

In certain aspects, the utility fluid contains aromatics, e.g., ≥70 wt.% aromatics, based on the weight of the utility fluid, such as ≥80 wt.%, or ≥90 wt. %. Typically, the utility fluid contains ≤10 wt. % ofparaffin, based on the weight of the utility fluid. For example, theutility fluid can contain ≥95 wt. % of aromatics, ≤5 wt. % of paraffin.Optionally, the utility fluid has a final boiling point ≤750° C. (1,400°F.), e.g., ≤570° C. (1,050° F.), such as ≤430° C. (806° F.). Suchutility fluids can contain ≥25 wt. % of 1-ring and 2-ring aromatics(e.g., those aromatics having one or two rings and at least one aromaticcore), based on the weight of the utility fluid. Utility fluids having arelatively low final boiling point can be used, e.g., a utility fluidhaving a final boiling point ≤400° C. (750° F.). The utility fluid canhave an 10% (weight basis) total boiling point ≥120° C., e.g., ≥140° C.,such as ≥150° C. and/or a 90% total boiling point ≤430° C., e.g., ≤400°C. Suitable utility fluids include those having a true boiling pointdistribution generally in the range from 175° C. (350° F.) to about 400°C. (750° F.). A true boiling point distribution can be determined, e.g.,by conventional methods such as the method of A.S.T.M. D7500, which canbe extended by extrapolation when the true boiling point distributionhas a final boiling point that is outside the range encompassed by theA.S.T.M. method. In certain aspects, the utility fluid has a massdensity ≤0.91 g/mL, e.g., ≤0.90 g/mL, such as ≤0.89 g/mL, or ≤0.88 g/mL,e.g., in the range of 0.87 g/mL to 0.90 g/mL.

The utility fluid typically contains aromatics, e.g., ≥95.0 wt. %aromatics, such as ≥99.0 wt. %. For example, the utility fluid cancontain ≥75 wt. % based on the weight of the utility fluid of one ormore of benzene, ethylbenzene, trimethylbenzene, xylenes, toluene,naphthalenes, alkylnaphthalenes (e.g., methylnaphtalenes), tetralins, oralkyltetralins (e.g., methyltetralins), e.g., ≥90 wt. %, or ≥95 wt. %,or ≥99.0 wt. %, such as ≥99.9 wt. %. It is generally desirable for theutility fluid to be substantially free of molecules having alkenylfunctionality, particularly in aspects utilizing a hydroprocessingcatalyst having a tendency for coke (e.g., pyrolytic and/or polymericparticles) formation in the presence of such molecules. In certainaspects, the utility fluid contains ≤10.0 wt. % of ring compounds havingC₁-C₆ sidechains with alkenyl functionality, based on the weight of theutility fluid.

In some examples, the utility fluid can include ≥90 wt. % of asingle-ring aromatic, including those having one or more hydrocarbonsubstituents, such as from 1 to 3 or 1 to 2 hydrocarbon substituents.Illustrative hydrocarbon substituents or hydrocarbon groups can be orinclude, but are not limited to, C₁-C₆ alkyls, where the hydrocarbongroups can be branched or linear and the hydrocarbon groups can be thesame or different.

In some examples, the utility fluid can be substantially free ofmolecules having terminal unsaturates, for example, vinyl aromatics. Asused herein, the term “substantially free” means that the utility fluidincludes 10 wt. % or less, e.g., 5 wt. % or less or 1 wt. % or less, ofterminal unsaturates, based on the weight of the utility fluid. Theutility fluid can include ≥50 wt. % of molecules having at least onearomatic core, e.g., ≥60 wt. % or ≥70 wt. %, based on the weight of theutility fluid. In some examples, the utility fluid can include ≥60 wt. %of molecules having at least one aromatic core and 1 wt. % or less ofterminal unsaturates, e.g., vinyl aromatics, based on the weight of theutility fluid.

In aspects where hydroprocessing is envisioned, e.g., hydroprocessing ofthe first lower-density portion, the utility fluid typically containssufficient amount of molecules having one or more aromatic cores as aprocessing aid, e.g., to effectively increase run length of the tarhydroprocessing process. For example, the utility fluid can contain≥50.0 wt. % of molecules having at least one aromatic core (e.g., ≥60.0wt. %, such as ≥70 wt. %) based on the total weight of the utilityfluid. In an aspect, the utility fluid contains (i) ≥60.0 wt. % ofmolecule having at least one aromatic core and (ii)≤1.0 wt. % of vinylaromatics, the weight percent being based on the weight of the utilityfluid.

The utility fluid can be one having a high solvency, as measured bysolubility blending number (“S_(Fluid)”). For example, the utility fluidcan have a S_(Fluid)≥90, e.g., ≥100, ≥110, ≥120, ≥150, ≥175, or ≥200.Additionally or alternatively, S_(Fluid) can be ≤200, e.g., ≤175, ≤150,≤125, ≤110, or ≤100. Ranges expressly disclosed include combinations ofany of the above-enumerated values.

Additionally or alternatively, the utility fluid may be characterized bya dynamic viscosity of that is typically less than that of the tar-fluidmixture. In particular aspects, the dynamic viscosity of the tar-fluidmixture may be ≥0.1 cPoise, e.g., ≥0.5 cPoise, ≥1 cPoise, ≥2.5 cPoiseor, ≥4 cPoise, at a temperature of about 50° C. to about 250° C., suchas about 100° C. Additionally or alternatively, the dynamic viscosity ofthe tar-fluid mixture may be ≤5 cPoise, e.g., ≤4 cPoise, ≤2.5 cPoise, ≤1cPoise, ≤0.5 cPoise, or ≤0.25 cPoise, at a temperature of about 50° C.to about 250° C., such as about 100° C. Ranges expressly disclosedinclude combinations of any of the above-enumerated values. In someaspects, the dynamic viscosity of the utility fluid is adjusted so thatwhen combined with the SCT composition to produce the tar-fluid mixture,solids having a size larger than 25 μm settle out of the tar-fluidmixture to provide the solids-enriched portion (the extract) andsolids-depleted portions (the raffinate) described herein, moreparticularly to adjust the viscosity to also enable the amount of solidsremoval and throughput of the solids-depleted portion from the process.

Optional Separation Fluids

The first and second separation fluids each can be selectedindependently. Each can be selected from among hydrocarbon liquid havinga mass density that is less than that of the SCT composition, e.g., ≤1%that of the feed, such as ≤5%, or ≤10%. Although it is not required, thefirst and second separation fluids can have substantially the samecomposition and can be referred to as “separation fluid”. The separationfluid can be any hydrocarbon liquid, typically a non-polar hydrocarbon,or mixture thereof. In some aspects, the separation fluid may be aparaffinic hydrocarbon or a mixture or paraffinic hydrocarbons.Particular paraffinic fluids include C₅ to C₂₀ hydrocarbons and mixturesthereof, particularly C₅ to C₁₀ hydrocarbons, e.g. hexane, heptane, andoctane. Such fluids may be particularly useful when subsequenthydroprocessing is not desired. In certain aspects, the separation fluidhas a mass density ≤0.91 g/mL, e.g., ≤0.90 g/mL, such as ≤0.89 g/mL, or≤0.88 g/mL, e.g., in the range of 0.87 to 0.90 g/mL.

When a distinct separation fluid is used in producing the tar-fluidmixture (namely, a separation fluid having a substantially differentcomposition from that of the utility fluid) the separation fluid can bepresent in the tar-fluid mixture in an amount ≤35 wt. %, e.g., ≤30 wt.%, ≤25 wt. %, ≤20 wt. %, ≤15 wt. %, ≤10 wt. %, ≤5 wt. %, ≤2.5 wt. %, or≤1.5 wt. %, based on the total weight of fluid in the tar-fluid mixture.Additionally or alternatively, the separation fluid may be present in anamount ≥ to 0 wt. %, e.g., ≥1.5 wt. %, ≥2.5 wt. %, ≥5 wt. %, ≥10 wt. %,≥15 wt. %, ≥20 wt. %, ≥25 wt. %, or ≥30 wt. %, based on the total weightof the fluid in the tar-fluid mixture. Ranges expressly disclosedinclude combinations of any of the above-enumerated values. It istypical in these and other aspects for separation fluid (when used) andSCT composition together to be ≥50 wt. % of the balance of the tar-fluidmixture (the balance being the part of the tar-fluid mixture that is notutility fluid+the recycled portion of the second lower-density portion),e.g., ≥75 wt. %, such as ≥90 wt. %, or ≥95 wt. %, or ≥99 wt. %.

The tar-fluid mixture can contain both utility fluid and separationfluid. Particularly in aspects where tar-fluid mixture components arenot subjected to subsequent hydroprocessing, the tar-fluid mixture maycomprise ≥30 wt. % of a separation fluid. Thus, in some aspects, thefluid of the tar-fluid mixture (i.e., any utility fluid present in thetar-fluid mixture plus any separation fluid present in the tar-fluidmixture) may contain ≥50 wt. % separation fluid, e.g., ≥60 wt. %, ≥70wt. %, ≥80 wt. %, ≥90 wt. %, ≥95 wt. %, ≥97.5 wt. %, ≥99 wt. %, or 100wt. % separation fluid, based on the total weight of the tar-fluidmixture. Additionally or alternatively, the tar-fluid mixture mayinclude ≤99 wt. % separation fluid, e.g., ≤97.5 wt. %, ≤95 wt. %, ≤90wt. %, ≤80 wt. %, ≤70 wt. %, or ≤60 wt. % separation fluid, based on thetotal weight of the tar-fluid mixture. Ranges expressly disclosedinclude combinations of any of the above-enumerated values.

Aspects of the invention which include separating from the tar-fluidmixture a first higher-density portion and a first lower-density portionin a first SCT separation stage will now be described in more detail.The invention is not limited to these aspects, and this descriptionshould not be interpreted as excluding other forms of separation.

First SCT Separation—Separating the First Higher-Density and FirstLower-Density Portions from the Tar-Fluid Mixture

The first higher-density and lower-density portions can be separatedfrom the tar-fluid mixture by any means suitable for achieving thespecified separation, including one or more of sedimentation,filtration, and extraction. Conventional separations technology can beutilized, but embodiments are not limited thereto. For example, thefirst lower-density portion may be separated from the tar-fluid mixtureby decantation, filtration and/or boiling point separation (e.g., one ormore distillation towers, splitters, flash drums, or any combinationthereof). The first higher-density portion may be separated from thetar-fluid mixture in a similar manner, e.g., by removing the firsthigher-density portion from the separation stage as a bottoms portion.The first higher-density portion and the first lower-density portion canbe separated from the tar-fluid mixture in any order, e.g.,substantially simultaneously, by first separating the firsthigher-density portion and then separating the first lower-densityportion from the first higher-density portion, or vice versa. In someaspects the first lower-density portion and the first higher-densityportion are separated by exposing the tar-fluid mixture to a centrifugalforce, e.g., by employing one or more centrifuges in the separationstage.

Inducing the Centrifugal Force

In some aspects, the tar-fluid mixture containing the SCT, solids (e.g.,pyrolytic coke, polymeric coke, and/or inorganics), and the firstutility fluid and/or first separation fluid is provided to a centrifugefor exposing the tar-fluid mixture to a centrifugal force sufficient toform at least a higher-density portion and a lower-density portion.Optionally, the tar-fluid mixture is subjected to one or more stages offiltration, e.g., to remove solids having a size ≥5000 μm, e.g., ≥3000μm, such as ≥2000 μm, or ≥1000 μm. In certain aspects, solids present inthe tar-fluid mixture have sizes in the range of from less than 1 μm to3000 μm, e.g., in a range of about 0.5 μm to 2000 μm. Typically, ≥75 wt.% of the solids have a size ≤2000 μm, e.g., ≥90 wt. %, such as ≥95 wt.%, or ≥99 wt. %. Typically, ≥75 wt. % of the solids have a size in therange of from 50 μm to 88 μm, e.g., ≥90 wt. %, such as ≥95 wt. %, or ≥99wt. %.

Typically, the tar-fluid mixture in the centrifuge exhibits asubstantially uniform circular motion as a result of an applied centralforce. Depending on reference-frame choice, the central force can bereferred to as a centrifugal force (in the reference-frame of thetar-fluid mixture) or a centripetal force (in the reference frame of thecentrifuge). The process may be performed in a batch, semi-batch orcontinuous manner.

The centrifuge may be configured to apply heat to the tar-fluid mixture,e.g., by heating the tar-fluid mixture to an elevated temperature. Insome aspects, inducing the centrifugal force also includes heating thetar-fluid mixture to a temperature of about 20° C., about 25° C., about30° C., about 40° C., about 50° C., about 55° C., or about 60° C. toabout 65° C., about 70° C., about 80° C., about 85° C., about 90° C.,about 95° C., about 100° C., about 110° C., about 120° C., or greater.For example, while centrifuging, the tar-fluid mixture can be heated toa temperature of about 20° C. to about 120° C., about 20° C. to about100° C., about 30° C. to about 100° C., about 40° C. to about 100° C.,about 50° C. to about 100° C., about 60° C. to about 100° C., about 70°C. to about 100° C., about 80° C. to about 100° C., about 90° C. toabout 100° C., about 20° C. to about 80° C., about 30° C. to about 80°C., about 40° C. to about 80° C., about 50° C. to about 80° C., about60° C. to about 80° C., or about 70° C. to about 80° C.

The centrifugal force may be applied for any amount of time. Typicallythe centrifugal force is applied for ≥1 minute, e.g., ≥5 minutes, ≥10minutes, ≥30 minutes, ≥60 minutes, or ≥120 minutes. Additionally oralternatively, the centrifugal force may be applied for ≤120 minutes,≤60 minutes, ≤30 minutes, ≤10 minutes, or ≤5 minutes. Ranges expresslydisclosed include combinations of any of the above-enumerated values;e.g., about 1 minute to about 120 minutes, about 5 minutes to about 120minutes, about 10 minutes to about 120 minutes, about 30 minutes toabout 120 minutes, or about 60 minutes to about 120 minutes. Thecentrifugal force may be applied for any amount of force or speed. Forexample, a sufficient force will be provided by a centrifuge operatingat about 1,000 rpm to about 10,000 rpm, about 2,000 rpm to about 7,500rpm, or about 3,000 rpm to about 5,000 rpm.

Centrifuging the tar-fluid mixture typically results in separating fromthe tar-fluid mixture at least (i) an extract comprising, consistingessentially of, or consisting of a first higher-density portion of thetar-fluid mixture and (ii) a raffinate comprising, consistingessentially of, or consisting of a first lower-density portion. In otherwords, exposing the tar-fluid mixture to the centrifugal force resultsin the removal of at least the higher-density portion (the extract) fromthe tar-fluid mixture. When the process is operated continuously orsemi-continuously, at least two streams can be conducted away from thecentrifuging: one stream containing the extract and another streamcontaining the raffinate. Centrifuges with such capabilities arecommercially available, but the invention is not limited thereto.

Typically centrifuging is sufficient to segregate ≥80 wt. %, ≥90 wt. %,≥95 wt. %, ≥99 wt. % of solids in the tar-fluid mixture (including theparticles in the tar-fluid mixture) having size ≥2 μm, e.g., ≥10 μm,such as ≥20 μm, or ≥25 μm, into the first higher-density portion (e.g.,the extract), the wt. % being based on the total weight of solids in thehigher-density and lower-density portions. Where subsequenthydroprocessing of the raffinate is envisioned, the higher-densityportion contains ≥95 wt. %, particularly ≥99 wt. %, of solids having asize of ≥2 μm, e.g., ≥10 μm, such as ≥20 μm, or ≥25 μm. In otheraspects, e.g., where the first lower-density portion (e.g., theraffinate) is not subjected to hydroprocessing, filtration should besufficient to segregate at least 80 wt. % of the solids into the firsthigher-density portion.

While the description focuses on separating a first higher-densityportion and a first lower-density portion, other embodiments envisionthat the components of the first tar-fluid mixture may be morediscretely segregated and extracted, e.g., very light componentssegregating to the top of the mixture, a portion that contains primarilythe fluid therebelow, an upgraded tar portion, tar heavies, or solids atthe bottom of the centrifuge chamber. Each of these portions, orcombinations thereof, may be selectively removed from the mixture as oneor more raffinates.

The First Lower-Density Portion

The first lower-density portion can be conducted away for one or more ofstorage, blending with other hydrocarbons, or further processing, e.g.,for SATC. The first lower-density portion generally has a desirableinsolubility number, e.g., an insolubility number that is less than thatof the SCT composition and/or less than that of the higher-densityportion. Typically, the insolubility number of the first lower-densityportion (I_(FLD)) is ≥20, e.g., ≥30, ≥40, ≥50, ≥60, ≥70, ≥80, ≥90, ≥100,≥110, ≥120, ≥130, ≥140, or ≥150. Additionally or alternatively, theI_(FLD) may be ≤150, e.g., ≤140, ≤130, ≤120≤110, ≤100, ≤90, ≤80, ≤70,≤60, ≤50, ≤40, or ≤30. Ranges expressly disclosed include combinationsof any of the above-enumerated values; e.g., about 20 to about 150,about 20 to about 140, about 20 to about 130, about 20 to about 120,about 20 to about 110, about 20 to about 100, about 20 to about 90,about 20 to about 80, about 20 to about 70, about 20 to about 60, about20 to about 50, about 20 to about 40, or about 20 to about 30. Thoseskilled in the art will appreciate that hydrocarbon separationstechnology is imperfect, and, consequently, a small amount of solids maybe present in the first lower-density portion, e.g., an amount of solidsthat is ≤0.1 times the amount of solids in the tar-fluid mixture, suchas ≤0.01 times. In aspects where at least part of the firstlower-density portion is hydroprocessed, e.g., by a SATC process,solids-removal means (e.g., one or more filters) are typically employedbetween the separation stage and the hydroprocessing stage.

The ratio of the insolubility number of the first lower-density portion,I_(FLD), to the insolubility number of the SCT composition, I_(TC), is≤0.95, e.g., ≤0.90, ≤0.85, ≤0.80, ≤0.75, ≤0.70, ≤0.65, ≤0.60, ≤0.55,≤0.50, ≤0.40, ≤0.30, ≤0.20, or ≤0.10. Additionally or alternatively, theratio of I_(FLD) to I_(TC) may be ≥0.10, e.g., ≥0.20, ≥0.30, ≥0.40,≥0.50, ≥0.55, ≥0.60, ≥0.65, ≥0.70, ≥0.75, ≥0.80, ≥0.85, or ≥0.90. Rangesexpressly disclosed include combinations of any of the above-enumeratedvalues, e.g., about 0.10 to 0.95, about 0.20 to 0.95, about 0.30 to0.95, about 0.40 to 0.95, about 0.50 to 0.95, about 0.55 to 0.95, about0.60 to 0.95, about 0.65 to 0.95, about 0.70 to 0.95, about 0.75 to0.95, about 0.80 to 0.95, about 0.85 to 0.95, or about 0.90 to 0.95.

The First Higher-Density Portion The first higher density portiontypically comprises solids having a size ≤5000 μm, e.g., ≤2000 μm, suchas ≤1000 μm; and optionally contains liquid such as utility fluid and/orseparation fluid carried over from the separation (e.g., from thecentrifuging). For example, the first higher density portion can containsolids in an amount in the range of 1 wt. % to 25 wt. % of solids havinga size ≤5000 μm (or ≤3000 μm, or ≤2000 μm) such as 5 wt. % to 15 wt. %based on the weight of the first higher density portion. In certainaspects, the first higher density portion contains solids having a sizein a range of ≤1 μm to 5000 μm, e.g., from 0.1 μm to 3000 μm, e.g., in arange of about 0.5 μm to 2000 μm. Typically, ≥75 wt. % of the solidshave a size ≤2000 μm, e.g., ≥90 wt. %, such as ≥95 wt. %, or ≥99 wt. %.Typically, ≥75 wt. % of the solids have a size in the range of from 50μm to 88 μm, e.g., ≥90 wt. %, such as ≥95 wt. %, or ≥99 wt. %.

The first higher-density portion, particularly the liquid-phase partthereof, may have an insolubility number, I_(FHD), ≥20, ≥40, ≥70, ≥90,≥100, ≥110, ≥120, ≥130, ≥140, or ≥150. Additionally or alternatively,I_(FHD), may be ≤40, ≤70, ≤90, ≤100, ≤110, ≤120, ≤130, ≤140, or ≤150.Ranges expressly disclosed include combinations of any of theabove-enumerated values; e.g., about 20 to about 150, about 40 to about150, about 70 to about 150, about 90 to about 150, about 100 to about150, about 110 to about 150, about 120 to about 150, about 130 to about150, or about 140 to about 150.

Additionally or alternatively, the first higher-density portion cancontain asphaltenes and/or tar heavies. In some aspects, the firsthigher-density portion, particularly the liquid portion thereof,contains ≥50 wt. % asphaltenes, e.g., ≥60 wt. %, ≥75 wt. %, based on thetotal weight of the first higher-density portion. The firsthigher-density portion may include ≤10 wt. %, e.g., ≤7.5 wt. %, ≤5 wt.%, ≤2.5 wt. %, ≤2 wt. %, ≤1.5 wt. %, or ≤1 wt. %, of the totalasphaltene content of the SCT composition. The first higher-densityportion may include ≥1 wt. %, e.g., ≥1.5 wt. %, ≥2 wt. %, ≥2.5 wt. %, ≥5wt. %, or ≥7.5 wt. %, of the total asphaltene content of the SCTcomposition. Ranges expressly disclosed include combinations of any ofthe above-enumerated values; e.g., 1 wt. % to 10 wt. %, 1 wt. % to 7.5wt. %, 1 wt. % to 5 wt. %, 1 wt. % to 2.5 wt. %, 1 wt. % to 2 wt. %, or1 wt. % to 1.5 wt. % of the total asphaltene content of the SCTcomposition. Removal of lower amounts of the asphaltene content may bepreferred. For example, it has been surprisingly found that thesegregation of even small amounts of asphaltenes into the higher-densityportion has a surprising impact on the insolubility number of the firstlower-density portion. While not wishing to be bound by any theory ormodel, it is believed that the presence of relatively high-densityasphaltenes in the SCT composition have a much greater impact oninsolubility number than do lower-density asphaltenes. Thus, arelatively large amount of problematic molecules can be separated,leaving in the first lower-density portion molecules that willcontribute to the over-all yield of the process.

The benefits of the process may be obtained even when the firsthigher-density portion contains a relatively small fraction of the SCTcomposition. The first higher-density portion may contain ≤10 wt. %,e.g., ≤7.5 wt. %, ≤5 wt. %, ≤2.5 wt. %, ≤2 wt. %, ≤1.5 wt. %, or ≤1 wt.% of the total weight of the SCT composition. Ranges expressly disclosedinclude combinations of any of the above-enumerated values; e.g., 1 wt.% to 10 wt. %, 1 wt. % to 7.5 wt. %, 1 wt. % to 5 wt. %, 1 wt. % to 2.5wt. %, 1 wt. % to 2 wt. %, or 1 wt. % to 1.5 wt. % of the total weightof the SCT composition. The removal of a relatively small weightfraction may surprisingly be accompanied by a relatively largeimprovement in the insolubility number of the first lower-densityportion. Solids present in the extract optionally have a mass density≥1.05 g/mL, e.g., ≥1.10 g/mL, such as ≥1.2 g/mL, or ≥1.3 g/mL, or in therange of from about 1.05 g/mL to 1.5 g/mL.

The first higher-density portion typically comprises ≥50 wt. % of anySCT solids remaining after the first thermal treatment, e.g., ≥75 wt. %,such as ≥90 wt. %, or ≥99 wt. The first higher density portion typicallyfurther comprises ≥50 wt. % of any of any solids in the SCT compositionthat formed during or as a result of the first thermal treatment, e.g.,≥75 wt. %, such as ≥90 wt. %, or ≥99 wt. %. The first higher-densityportion is processed in a second thermal treatment and optional physicalreduction in the size of solids present in the first higher-densityportion (e.g., by comminuting, such as grinding) in order to lessen theamount of solids. This processing can be carried out in the presence ofdiluent.

Optional Size Reduction—Physical Processes

Physical processes for size reduction of solids such as particles(grinding, etc.—collectively referred to as comminuting) are optionallycarried out on the first higher-density portion to form a comminutedhigher-density portion. Examples of physical processes for sizereduction can include grinding, ball milling, ablation in an ablationdrum, and/or other mechanical size reduction processes. Physicalprocesses for size reduction can be in contrast to chemical processesfor size reduction. For example, as described herein, at least a portionof sufficiently small solids (e.g., particles) in a SCT fraction (orother pyrolysis tar fraction) can be hydroprocessed (such as under SATCconditions) to convert the small solids to liquid products. Duringcertain SATC processes, a combination of elevated temperature, elevatedpressure, the presence of chemical reagents, and/or the presence ofcatalysts are used to induce chemical reactions. The chemical reactionsresult in changes in chemical compositions that can then result in asize reduction. By contrast, in some aspects, the physical sizereduction can result in solids with roughly similar compositions (withpossible exception of surface layers) both before and after the sizereduction.

After performing a first physical size reduction process on the firsthigher-density portion, the weight of solids having a size of 25 μm ormore in the comminuted higher-density portion can be further decreasedin one or more additional stages. Effluent from these stages can have aweight of solids having a size of 25 μm or more that is 85% or lessrelative to the weight of such solids in the first higher-densityportion or diluted first higher-density portion (as the case may be), or75% or less, or 65% or less, or 50% or less, such as down to 10% orpossibly still lower.

Suitable equipment for reducing the size of solids is commerciallyavailable, but the invention is not limited thereto. Grinders, ballmills, and ablators are suitable. More generally, any convenient processfor reducing the size of solids, such as coke fines, can be used.

Since the first higher-density portion is typically leaner in totalfluid (any first utility fluid+any first separation fluid) in comparisonwith the tar-fluid mixture, a diluted first higher-density portion maybe formed by introducing into the first higher-density portion a secondutility fluid and/or a second separation fluid. These diluents areoptional, and may be added to the first higher-density portion, e.g., asa flux and/or as an aid in (i) the second thermal treatment and/or (ii)the separation of the second higher-density and second lower-densityportions. These diluents can be added before and/or after the optionalsize reduction (e.g., optional grinding). For example, the secondutility fluid can be added before and/or after optional; grinding. Thesecond utility fluid can be selected from among the same compositionsspecified for the first utility fluid, and typically the first andsecond utility fluids have substantially the same composition.

Diluted First Higher-Density Portion

When desired, e.g., as an aid to process-ability of the firsthigher-density portion, diluent (typically comprising the second utilityfluid and/or the second separation fluid) may be added to the firsthigher-density portion to form a diluted first higher-density portion.Diluent, when used can correspond to 20 wt. % to 60 wt. % of dilutedfirst higher-density portion, or 20 wt. % to 50 wt. %, or 30 wt. % to 60wt. %. Even if diluent is added to the first higher-density portionbefore a size reduction process, additional diluent can be added aftersize reduction to further facilitate heat soaking of the firsthigher-density portion (or comminuted higher-density portion) present inthe diluted first higher-density portion. Typically, the diluentcomprises ≥50 wt. % of utility fluid, based on the weight of thediluent, e.g., ≥75 wt. %, such as ≥90 wt. %. Typically, ≥90 wt. % of thebalance of the diluent comprises separation fluid.

In certain aspects, the diluent does not contain the second separationfluid. It has been discovered that processing the diluted firsthigher-density portion in the second thermal treatment before separationof the second higher-density portion and the second lower-densityportion can obviate the need for the second separation fluid.

It has been found to be advantageous for the diluent to include a secondutility fluid, and to carry out the second thermal treatment underdifferent conditions that the first thermal treatment. Doing so has beenfound to provide for dissolution of at least a portion of the polymericsolids in the first higher-density portion, such as those formed duringand/or as a result of the first thermal treatment, and on-purposedepolymerization of these polymeric solids. In addition, the secondutility fluid dilutes the depolymerized products of the second thermaltreatment which is observed to lessen or eliminate repolymerization ofthese products. The second utility fluid can be selected from amongutility fluids comprising a reactive composition such as SCGO. When sucha second utility fluid is present in the diluted first higher-densityportion during the second thermal treatment, a reactivity decrease(e.g., a decrease in SCGO reactivity) is observed. This featuresimulates the use of (and obviates the need for) a higher-value diluent,such as utility fluid recovered from a SATC process (e.g., a mid-cut).In other words, the diluent can comprise SCGO, mid-cut, or a combinationthereof.

In some aspects, the diluent can contain ≥65 wt. % of utility fluid,e.g., ≥75 wt. %, ≥80 wt. %, ≥85 wt. %, ≥90 wt. %, or ≥95 wt. % utilityfluid, based on the total weight of the diluent. Additionally oralternatively, the diluent may contain ≤100 wt. % utility fluid, e.g.,≤95 wt. %, ≤90 wt. %, ≤85 wt. %, ≤80 wt. %, ≤75 wt. %, or ≤70 wt. %utility fluid, based on the total weight of the diluent. Rangesexpressly disclosed include combinations of any of the above-enumeratedvalues, e.g., about 65 wt. % to about 100 wt. %, about 75 wt. % to about100 wt. %, about 80 wt. % to about 100 wt. %, about 85 wt. % to about100 wt. %, about 90 wt. % to about 100 wt. %, or about 95 wt. % to about100 wt. % utility fluid. In certain aspects, the diluent is utilityfluid.

In the following description of the diluted first higher-density portionand the second thermal treatment, it should be understood that the firsthigher-density portion can be the comminuted first higher-densityportion in aspects where an optional comminuting step is carried out.Typically, the diluted first higher-density portion contains ≥5 wt. % ofthe first higher-density portion, e.g., ≥10 wt. %, ≥20 wt. %, ≥30 wt. %,≥40 wt. %, ≥50 wt. %, ≥60 wt. %, ≥70 wt. %, ≥80 wt. %, or ≥90 wt. %,based on the total weight of the diluted first higher-density portion.Those skilled in the art will appreciate that the amount of utilityfluid in the diluted first higher-density portion includes (i) anyresidual first utility fluid transferred from the tar-fluid mixture tothe first higher-density portion and (ii) the second utility fluid.

In addition to the first higher-density portion, the dilutedhigher-density portion generally contains ≥5 wt. % diluent, e.g., ≥10wt. %, ≥20 wt. %, ≥30 wt. %, ≥40 wt. %, ≥50 wt. %, ≥60 wt. %, ≥70 wt. %,≥80 wt. %, or ≥90 wt. %, based on the total weight of the dilutedhigher-density portion (e.g., a combined weight of the firsthigher-density portion, any residual first utility fluid carried overfrom the tar-fluid mixture, any first separation fluid carried over fromthe tar-fluid mixture, any second utility fluid, and any secondseparation fluid. Additionally or alternatively, the diluted firsthigher-density portion may include ≤10 wt. % fluid, e.g., ≤20 wt. %, ≤30wt. %, ≤40 wt. %, ≤50 wt. %, ≤60 wt. %, ≤70 wt. %, ≤80 wt. %, ≤90 wt. %,or ≤95 wt. % diluent, based on the total weight of the diluted firsthigher-density portion. Ranges expressly disclosed include combinationsof any of the above-enumerated values, e.g., about 5 wt. % to about 95wt. %, about 5 wt. % to about 90 wt. %, about 5 wt. % to about 80 wt. %,about 5 wt. % to about 70 wt. %, about 5 wt. % to about 60 wt. %, about5 wt. % to about 50 wt. %, about 5 wt. % to about 40 wt. %, about 5 wt.% to about 30 wt. %, about 5 wt. % to about 20 wt. %, or about 5 wt. %to about 10 wt. % fluid.

In some aspects, the diluted first higher-density portion has asolubility blending number of less than 150, such as about 140 or less,about 130 or less, about 120 or less, as about 115 or less, about 110 orless, about 105 or less, about 100 or less, about 95 or less, or about90 or less. In some examples, the diluted first higher-density portionhas a solubility blending number of about 70, about 80, about 85, about90, about 95, about 100, about 105, about 110, about 115, about 120,about 130, about 140, or about 150. For example, the diluted firsthigher-density portion has a solubility blending number of about 70 toabout 150, about 70 to about 130, about 70 to about 125, about 70 toabout 120, about 70 to about 115, about 70 to about 110, about 70 toabout 105, about 70 to about 100, about 70 to about 95, about 70 toabout 90, about 70 to about 85, about 80 to about 130, about 80 to about125, about 80 to about 120, about 80 to about 115, about 80 to about110, about 80 to about 105, about 80 to about 100, about 80 to about 95,about 80 to about 90, about 85 to about 130, about 85 to about 125,about 85 to about 120, about 85 to about 115, about 85 to about 110,about 85 to about 105, about 85 to about 100, about 85 to about 95,about 85 to about 90, about 90 to about 130, about 90 to about 125,about 90 to about 120, about 90 to about 115, about 90 to about 110,about 90 to about 105, about 90 to about 100, or about 90 to about 95.

The dynamic viscosity of the diluted first higher-density portion can beless than that of the first higher-density portion. In some aspects, thedynamic viscosity of the diluted first higher-density portion may be≥0.5 cPoise, e.g., ≥1 cPoise, ≥2.5 cPoise, ≥5 cPoise, ≥7.5 cPoise, at atemperature of about 50° C. to about 250° C., such as about 100° C.Additionally or alternatively, the dynamic viscosity of the tar-fluidmixture may be ≤10 cPoise, e.g., ≤7.5 cPoise, ≤5 cPoise, ≤2.5 cPoise, ≤1cPoise, ≤0.75 cPoise, at a temperature of about 50° C. to about 250° C.,such as about 100° C. Ranges can include combinations of any of theabove-enumerated values, e.g., about 0.5 cPoise to about 10 cPoise,about 1 cPoise to about 10 cPoise, about 2.5 cPoise to about 10 cPoise,about 5 cPoise to about 10 cPoise, or about 7.5 cPoise to about 10cPoise, at a temperature of about 50° C. to about 250° C., such as about100° C.

The diluted first higher-density portion is subjected to an additionalthermal treatment. Aspects in which the second thermal treatmentincludes a second heat soak will now be described in more detail. Theinvention is not limited to these aspects, and this description shouldnot be interpreted as excluding forms of thermal treatment that do notinclude heat soaking.

Second Thermal Treatment

In other embodiments, the first higher-density portion or diluted firsthigher-density portion (as the case may be) is subjected to a secondthermal treatment, e.g., a second heat soaking. The second thermaltreatment can be carried out by heat soaking in at least one vessel ordrum. The heat soaking can include pyrolysis, e.g., thermal pyrolysis.

Certain forms of solids are present in the SCT when SCT is separatedfrom the steam cracker effluent. Other forms of solids, e.g., certainparticulates, form during and/or as a result of the first thermaltreatment, such as by polymerization of separated SCT in a tar knock-outdrum and/or primary fractionator. It has been found that (i) the SCTcomposition can contain both forms of solids, and (ii) when operatingthe first SCT separation under the specified conditions that ≥50 wt. %of solids in the SCT composition are transferred to the firsthigher-density portion, e.g., ≥75 wt. %, such as ≥90 wt. %, or ≥95 wt.%, or ≥99 wt. %. Surprisingly, it has been found that such solids can beconverted during and/or as a result of the second thermal treatment toform conversion products (typically in the liquid phase) having a massdensity that is in substantially the same range as that of the firstlower-density portion. The amount of material residing in the firstlower-density portion thus can be increased by (i) transferring at leasta portion of these conversion products of the second thermal treatmentto a second lower-density portion, and then recycling the secondlower-density portion to (i) the first lower density portion and/or (ii)a location in the process that is upstream of the separation from theSCT composition of the first lower-density portion. Typically, ≥50 wt. %of solids in the first higher-density portion are those produced duringthe first thermal treatment, e.g., ≥75 wt. %, such as ≥90 wt. %, ormore. FIG. 2 can be utilized to determine the amount of these solidsthat are converted in the specified second thermal treatment. While notwishing to be bound by any theory or model, it is believed that thesecond thermal treatment at least partially-converts (e.g., dissolves ordecomposes) solids present in the diluted first higher-density portion,particularly those solids produced (e.g., by polymerization) duringand/or as a result of the first thermal treatment. For a typical SCT,FIG. 2 indicates the amount of solids that are converted from a greatermass density to a lesser mass density (e.g., from a more dense solidphase and/or semi-solid phase to a less dense liquid phase) during or asa result of the second thermal treatment as a function of second thermaltreatment temperature for a time in the range of from 30 minutes to 60minutes. Those skilled in the art will appreciate that a similar curvecan be produced for other tars without undue experimentation.Conventional heat-soaking equipment can be used for carrying out thesecond heat soaking, e.g., one or more soaker drums, but the inventionis not limited thereto. The second heat soaking can be carried out for adesired temperature (“T_(HS2)”) and for a desired period of time(“t_(HS2)”), which are typically predetermined. T_(HS2) is typicallyabout 200° C., about 220° C., about 230° C., about 240° C., about 250°C., about 260° C., about 270° C., about 275° C., about 280° C., or about290° C. to about 295° C., about 300° C., about 310° C., about 320° C.,about 325° C., about 330° C., about 340° C., about 350° C., about 360°C., about 375° C., about 400° C., about 450° C., about 500° C., orhigher. For example, T_(HS2) can be in a range of from about 200° C. toabout 500° C., about 230° C. to about 500° C., about 250° C. to about500° C., about 280° C. to about 500° C., about 290° C. to about 500° C.,about 300° C. to about 500° C., about 320° C. to about 500° C., about350° C. to about 500° C., about 250° C. to about 450° C., about 280° C.to about 450° C., about 290° C. to about 450° C., about 300° C. to about450° C., about 320° C. to about 450° C., about 350° C. to about 450° C.,about 250° C. to about 400° C., about 280° C. to about 400° C., about290° C. to about 400° C., about 300° C. to about 400° C., about 320° C.to about 400° C., about 350° C. to about 400° C., about 250° C. to about350° C., about 280° C. to about 350° C., about 290° C. to about 350° C.,about 300° C. to about 350° C., about 320° C. to about 350° C., or about330° C. to about 350° C. Although it is not required to maintain thediluted first higher-density portion at a substantially-constanttemperature during the second heat soak (i.e., a substantially constanttemperature within the specified range of T_(HS2)), it is typical to doso. Time t_(HS2) can be about 2 min, about 5 min, about 10 min, about 12min, or about 15 min to about 20 min, about 25 min, about 30 min, about45 min, about 60 min, about 90 min, about 2 hr, about 3 hr, about 5 hr,or longer. For example, t_(HS2) can be in a range of about 5 min toabout 5 hr, about 5 min to about 3 hr, about 5 min to about 2 hr, about5 min to about 1 hr, about 5 min to about 45 min, about 5 min to about30 min, or about 5 min to about 20 min. In one or more examples, t_(HS2)is in a range of about 2 min, about 5 min, about 10 min, about 15 min,or about 20 min to about 30 min, about 45 min, about 60 min, about 90min, about 2 hr, about 3 hr, or about 5 hr to convert (e.g., dissolve ordecompose) solids (e.g., polymeric solids) in the first higher-densityportion or the diluted first higher-density portion (as the case may be)to material of a lesser density during or as a result of the secondthermal treatment.

It is observed that the second heat soak produces a thermally-treated,first higher-density portion having fewer solids than does the firsthigher-density portion before the second thermal treatment. In aspectswhere a diluent is used, the second heat soak produces athermally-treated, diluted first higher-density portion having fewersolids than does the diluted first higher-density portion. In one ormore embodiments, about 25 wt. %, about 30 wt. %, about 35 wt. %, orabout 40 wt. % to about 45 wt. %, about 50 wt. %, about 60 wt. %, about70 wt. %, about 75 wt. %, about 80 wt. %, about 85 wt. %, about 90 wt.%, about 92 wt. %, about 95 wt. %, about 97 wt. %, about 98 wt. %, about99 wt. %, or more of the solids (e.g., polymeric solids formed from thefirst thermal treatment) in the first higher-density portion or thediluted first higher-density portion (as the case may be) are converted(e.g., dissolved or decomposed) to a liquid material (typically oflesser density) during or as a result of the second thermal treatment.In some examples, at least 25 wt. %, at least 30 wt. %, at least 35 wt.%, at least 40 wt. %, at least 45 wt. %, at least 50 wt. %, at least 60wt. %, at least 70 wt. %, at least 75 wt. %, at least 80 wt. % to about85 wt. %, about 90 wt. %, about 92 wt. %, about 95 wt. %, about 97 wt.%, about 98 wt. %, about 99 wt. %, or more of the solids (e.g.,particles) in the first higher-density portion or the diluted firsthigher-density portion (as the case may be) are converted during or as aresult of the second thermal treatment. For example, about 25 wt. % toabout 99 wt. %, about 30 wt. % to about 99 wt. %, about 35 wt. % toabout 99 wt. %, about 40 wt. % to about 99 wt. %, about 45 wt. % toabout 99 wt. %, about 50 wt. % to about 99 wt. %, about 60 wt. % toabout 99 wt. %, about 70 wt. % to about 99 wt. %, about 75 wt. % toabout 99 wt. %, about 25 wt. % to about 95 wt. %, about 30 wt. % toabout 95 wt. %, about 35 wt. % to about 95 wt. %, about 40 wt. % toabout 95 wt. %, about 45 wt. % to about 95 wt. %, about 50 wt. % toabout 95 wt. %, about 60 wt. % to about 95 wt. %, about 70 wt. % toabout 95 wt. %, about 75 wt. % to about 95 wt. %, about 25 wt. % toabout 90 wt. %, about 30 wt. % to about 90 wt. %, about 35 wt. % toabout 90 wt. %, about 40 wt. % to about 90 wt. %, about 45 wt. % toabout 90 wt. %, about 50 wt. % to about 90 wt. %, about 60 wt. % toabout 90 wt. %, about 70 wt. % to about 90 wt. %, about 75 wt. % toabout 90 wt. %, about 25 wt. % to about 80 wt. %, about 30 wt. % toabout 80 wt. %, about 35 wt. % to about 80 wt. %, about 40 wt. % toabout 80 wt. %, about 45 wt. % to about 80 wt. %, about 50 wt. % toabout 80 wt. %, about 60 wt. % to about 80 wt. %, about 70 wt. % toabout 80 wt. %, or about 75 wt. % to about 80 wt. % of the of the solids(e.g., polymeric solids, such as polymeric particulates) formed from thefirst thermal treatment) in the first higher-density portion or thediluted first higher-density portion (as the case may be) are converted(e.g., dissolved or decomposed) during or as a result of the secondthermal treatment.

In certain aspects, the amount of solids (wt. %) in thethermally-treated first higher-density portion (“A₂”, based on theweight of the thermally-treated first higher-density portion) is lessthan the amount of solids (wt. %) in the first higher-density portion(“A₁”, based on the weight of the first higher-density portion), e.g.,A₂≤R*A₁, where R is a real number <1, e.g., one of 0.9, 0.8, 0.7, 0.6,0.5, 0.4, 0.3, 0.2, and 0.1. In other aspects, the amount of solids (wt.%) in the thermally-treated first higher-density portion (“A₂”, based onthe weight of the thermally-treated first higher-density portion) isless than the amount of solids (wt. %) in the diluted firsthigher-density portion (“A_(1d)”, based on the weight of the dilutedfirst higher-density portion), e.g., A₂≤R*A_(1d). It has been found thatthe relationships A₂≤R*A₁ and A₂≤R*Aid are achieved whether or not thecomminuting is carried out on first higher-density portion before thesecond thermal treatment, although a lesser value of R (“R_(c)”) can beachieved when the comminuting is carried out. R_(c) can be, e.g., R*0.9,such as R*0.8, or R*0.7. With or without comminuting, for example, A₂ isin the range of from 10% of A₁ to 40% of A₁, such as 15% of A₁ to 30% ofA₁, or 20% of A₁ to 25% of A₁.

The solids converted in the second thermal treatment are typicallyconverted mainly to liquid-phase compositions, e.g., ≥75 wt. % of theproducts of the solids conversion are in the liquid phase, such as ≥90wt. %, or ≥95 wt. %, or ≥99 wt. %.

The second thermal treatment, e.g., the second heat soaking, is observedto improve the properties of the first higher-density portion containedin the diluted first higher-density portion. Although at least a portionof the thermally-treated first higher-density portion is typicallysubjected to further processing (e.g., separation and recycle of asecond lower-density portion), the thermally-treated firsthigher-density portion is itself a useful product, e.g., as a fuel oil.This is so because the thermally-treated first higher-density portiontypically has a lesser reactivity and a lesser solids content ascompared to the first higher-density portion.

Representative thermally-treated first higher-density portions will nowbe described in more detail. The present disclosure is not limited tothese, and this description is not meant to foreclose otherthermally-treated first higher-density portions within the broader scopeof the present disclosure, such as those produced by forms of the secondthermal treatment that do not include a second hat soaking.

Thermally-Treated First Higher-Density Portion

The thermally-treated first higher-density portion typically has a finalboiling point of at least about 550° F.+(˜288° C.+). Boiling pointsand/or fractional weight distillation points can be determined by, forexample, ASTM D2892. The final boiling point of the thermally-treatedfirst higher-density portion can be dependent on the nature of thehigher-density portion, which in turn can depend on the steam crackingfeed's composition and steam cracking conditions.

That part of the thermally-treated first higher-density portion having aboiling point at atmospheric pressure ≥550° F. (≥288° C.+) typically hasa relatively low hydrogen content compared to other heavy oil fractions,e.g., those generally processed in a refinery or petrochemical setting.For example, that part of the thermally-treated first higher-densityportion can have a hydrogen content of about 8.0 wt. % or less, about7.5 wt. % or less, or about 7.0 wt. % or less, or about 6.5 wt. % orless, e.g., in a range of about 5.5 wt. % to about 8.0 wt. %, or about6.0 wt. % to about 7.5 wt. %.

That part of the thermally-treated first higher-density portion having aboiling point at atmospheric pressure ≥550° F. (≥288° C.+) is typicallyhighly aromatic in nature. The paraffin content of that part of thethermally-treated first higher-density portion can be about 2.0 wt. % orless, or about 1.0 wt. % or less, such as having substantially noparaffin content. The naphthene content of that part of thethermally-treated first higher-density portion can also be about 2.0 wt.% or less or about 1.0 wt. % or less, such as having substantially nonaphthene content. In some aspects, the combined paraffin and naphthanecontent of that part of the thermally-treated first higher-densityportion can be about 1.0 wt. % or less.

Aspects of the invention which include separating from thethermally-treated first higher-density portion a second higher-densityportion and a second lower-density portion will now be described in moredetail. The invention is not limited to these aspects, and thisdescription should not be interpreted as excluding other forms ofseparation within the broader scope of the invention. For simplicity,this separation is called a “second SCT separation”. Those skilled inthe art will appreciate that this identifier is used because thethermally-treated first higher-density portion is derived from an SCT.The use of this identifier should not be interpreted as limiting thesecond separation to separating streams from an SCT itself, e.g., an SCTthat has not been subjected to a first thermal treatment or a first SCTseparation.

Second SCT Separation—Separating the Second Higher-Density and SecondLower-Density Portions from the Thermally-Treated First Higher-DensityPortion

The second higher-density and lower-density portions can be separatedfrom the thermally-treated first higher-density portion by any meanssuitable for achieving the specified separation, including one or moreof sedimentation, filtration, and extraction. Conventional separationstechnology can be utilized, but embodiments are not limited thereto. Forexample, the second lower-density portion may be separated from thethermally-treated first higher-density portion by decantation,filtration and/or boiling point separation (e.g., one or moredistillation towers, splitters, flash drums, or any combinationthereof). The second higher-density portion may be separated from thethermally-treated first higher-density portion in a similar manner,e.g., by removing the second higher-density portion from the separationstage as a bottoms portion. The second higher-density portion and thesecond lower-density portion can be separated from the thermally-treatedfirst higher-density portion in any order, e.g., substantiallysimultaneously, by first separating the second higher-density portionand then separating the second lower-density portion from the secondhigher-density portion, or vice versa. In some aspects, the secondhigher-density portion and the second lower-density portion areseparated by exposing the thermally-treated first higher-density portionto a centrifugal force, e.g., by employing one or more centrifuges inthe separation stage.

The second higher-density portion and the second lower-density portionmay be separated from the thermally-treated first higher-density portionby any means suitable for forming the second higher-density and secondlower-density portions. Aspects using one or more centrifuge separationsin the second SCT separation stage will now be described in more detail.Embodiments are not limited to these aspects, as well as thisdescription is not to be interpreted as foreclosing the use ofadditional and/or alternative separations technologies, such as thosethat do not involve exposing the thermally-treated first higher-densityportion to a centrifugal force.

Inducing the Centrifugal Force

In some aspects, the thermally-treated first higher-density portioncontaining thermally-treated SCT, any diluent, and any solids remainingafter the second thermal treatment is provided to a second centrifugefor exposing the thermally-treated first higher-density portion to acentrifugal force sufficient to form at least a second higher-densityportion and a second lower-density portion. Typically, thethermally-treated first higher-density portion in the centrifugeexhibits a substantially uniform circular motion as a result of anapplied central force. Depending on reference-frame choice, the centralforce can be referred to as a centrifugal force (in the reference-frameof the thermally-treated first higher-density portion) or a centripetalforce (in the reference frame of the centrifuge). The process may beperformed in a batch, semi-batch or continuous manner.

The centrifuge may be configured to apply heat to the thermally-treatedfirst higher-density portion, e.g., by heating the thermally-treatedfirst higher-density portion to an elevated temperature. In someaspects, inducing the centrifugal force also includes heating thethermally-treated first higher-density portion to a temperature of about20° C., about 25° C., about 30° C., about 40° C., about 50° C., about55° C., or about 60° C. to about 65° C., about 70° C., about 80° C.,about 85° C., about 90° C., about 95° C., about 100° C., about 110° C.,about 120° C., or greater. For example, while centrifuging, thethermally-treated first higher-density portion can be heated to atemperature of about 20° C. to about 120° C., about 20° C. to about 100°C., about 30° C. to about 100° C., about 40° C. to about 100° C., about50° C. to about 100° C., about 60° C. to about 100° C., about 70° C. toabout 100° C., about 80° C. to about 100° C., about 90° C. to about 100°C., about 20° C. to about 80° C., about 30° C. to about 80° C., about40° C. to about 80° C., about 50° C. to about 80° C., about 60° C. toabout 80° C., or about 70° C. to about 80° C.

The centrifugal force may be applied for any amount of time. Typicallythe centrifugal force is applied for ≥1 minute, e.g., ≥5 minutes, ≥10minutes, ≥30 minutes, ≥60 minutes, or ≥120 minutes. Additionally oralternatively, the centrifugal force may be applied for ≤120 minutes,≤60 minutes, ≤30 minutes, ≤10 minutes, or ≤5 minutes. Ranges expresslydisclosed include combinations of any of the above-enumerated values;e.g., about 1 minute to about 120 minutes, about 5 minutes to about 120minutes, about 10 minutes to about 120 minutes, about 30 minutes toabout 120 minutes, or about 60 minutes to about 120 minutes. Thecentrifugal force may be applied for any amount of force or speed. Forexample, a sufficient force will be provided by a centrifuge operatingat about 1,000 rpm to about 10,000 rpm, about 2,000 rpm to about 7,500rpm, or about 3,000 rpm to about 5,000 rpm.

Centrifuging the thermally-treated first higher-density portiontypically results in separating from the thermally-treated firsthigher-density portion at least (i) an extract containing a secondhigher-density portion of the thermally-treated first higher-densityportion and (ii) a second raffinate or a second lower-density portion.In other words, exposing the thermally-treated first higher-densityportion to the centrifugal force results in the removal of at least thesecond higher-density portion (the second extract) from thethermally-treated first higher-density portion. When the process isoperated continuously or semi-continuously, at least two streams can beconducted away from the centrifuging: one stream containing the secondextract and another stream containing the second raffinate. Centrifugeswith such capabilities are commercially available.

Typically centrifuging is sufficient to segregate ≥80 wt. %, ≥90 wt. %,≥95 wt. %, ≥99 wt. % of solids having size ≥2 μm, e.g., ≥10 μm, such as≥20 μm, or ≥25 μm, into the second higher-density portion (e.g., thesecond extract), the wt. % being based on the total weight of solids inthe second higher-density and second lower-density portions. Wheresubsequent hydroprocessing of the second raffinate is envisioned, thesecond higher-density portion contains ≥95 wt. %, particularly ≥99 wt.%, of solids having a size ≥2 μm, e.g., ≥10 μm, such as ≥20 μm, or ≥25μm. In other aspects, filtration should be sufficient to segregate atleast 80 wt. % of the solids into the higher-density portion.

While the description focuses on a second higher-density portion and asecond lower-density portion, other embodiments envision that thecomponents of the thermally-treated first higher-density portion may bemore discretely segregated and extracted, e.g., very light componentssegregating to the top of the mixture, a portion that contains primarilythe diluent, an upgraded tar portion, tar heavies, or solids at thebottom of the centrifuge chamber. One or more of these portions may beselectively removed from the mixture as one or more raffinates.Typically, at least a portion of the second lower-density portion isrecycled (directly or indirectly) to the first centrifuge. The secondhigher-density portion can be sent away from the process, e.g., forstorage and/or further processing, including additional centrifuging.

The Second Lower-Density Portion

The second lower-density portion is generally removed from theseparation stage as a second raffinate, a portion of which (e.g., ≥50wt. %, ≥75 wt. %, ≥90 wt. %) can be conducted away for recycle, e.g., asa component of the tar-fluid mixture. In certain aspects, the secondlower-density portion is recycled and combined with one or more of (i)the steam cracker effluent, (ii) the SCT, (iii) the SCT composition,(iv) the tar-fluid mixture, before and/or during the separation of thefirst higher-density portion and the first lower-density portion, (v)the first higher-density portion, and (vi) the first lower-densityportion. In certain aspects, the second lower-density portion can addedto the SCT composition in an amount sufficient to from a part of or theentirety of the fluid utilized to form the tar-fluid mixture. In aspectswhere the first lower-density portion is subjected to hydroprocessing(e.g., SATC hydroprocessing), the recycling of at least a portion of thesecond lower-density portion provides for a greater yield of upgraded(e.g., hydroprocessed) tar, provides material and cost savings for tarupgrading processes, and produces fewer solids to be conducted away ascompared to conventional tar upgrading processes.

The second lower-density portion generally has a desirable insolubilitynumber, e.g., an insolubility number that is less than that of one ormore of (i) the SCT, (ii) the SCT composition, (iii) tar-fluid mixture,(iii) the first higher-density portion, and the second higher-densityportion. Typically, the insolubility number of the second lower-densityportion (I_(LD)) is ≥20, e.g., ≥30, ≥40, ≥50, ≥60, ≥70, ≥80, ≥90, ≥100,≥110, ≥120, ≥130, ≥140, or ≥150. Additionally or alternatively, theI_(LD) may be ≤150, e.g., ≤140, ≤130, ≤120≤110, ≤100, ≤90, ≤80, ≤70,≤60, ≤50, ≤40, or ≤30. Ranges expressly disclosed include combinationsof any of the above-enumerated values; e.g., about 20 to about 150,about 20 to about 140, about 20 to about 130, about 20 to about 120,about 20 to about 110, about 20 to about 100, about 20 to about 90,about 20 to about 80, about 20 to about 70, about 20 to about 60, about20 to about 50, about 20 to about 40, or about 20 to about 30. Thoseskilled in the art will appreciate that hydrocarbon separationstechnology is imperfect, and, consequently, a small amount of solids maybe present in the second lower-density portion, e.g., an amount ofsolids that is ≤0.1 times the amount of solids in the thermally-treatedfirst higher-density portion, such as ≤0.01 times. The ratio of theinsolubility number of the second lower-density portion, I_(LD), to theinsolubility number of the tar-fluid mixture, I_(TF), is ≤0.95, e.g.,≤0.90, ≤0.85, ≤0.80, ≤0.75, ≤0.70, ≤0.65, ≤0.60, ≤0.55, ≤0.50, ≤0.40,≤0.30, ≤0.20, or ≤0.10. Additionally or alternatively, the ratio ofI_(LD) to I_(TF) may be ≥0.10, e.g., ≥0.20, ≥0.30, ≥0.40, ≥0.50, ≥0.55,≥0.60, ≥0.65, ≥0.70, ≥0.75, ≥0.80, ≥0.85, or ≥0.90. Ranges expresslydisclosed include combinations of any of the above-enumerated values,e.g., about 0.10 to 0.95, about 0.20 to 0.95, about 0.30 to 0.95, about0.40 to 0.95, about 0.50 to 0.95, about 0.55 to 0.95, about 0.60 to0.95, about 0.65 to 0.95, about 0.70 to 0.95, about 0.75 to 0.95, about0.80 to 0.95, about 0.85 to 0.95, or about 0.90 to 0.95.

Typically at least a portion of the second lower density portion is inthe liquid phase, e.g., ≥25 wt. % such as ≥50 wt. %, or ≥75 wt. %, or≥90 wt. %. Typically ≥50 wt. % of solids converted (e.g., fromparticulate form) during and/or as a result of the second thermaltreatment resides in the second lower-density portion, e.g., ≥75 wt. %,such as ≥90 wt. %, or ≥99 wt. %. Typically, ≥50 wt. % of diluent in thediluted first higher-density portion resides in the second lower-densityportion, e.g., ≥50 wt. %, such as ≥75 wt. %, or ≥90 wt. %, or ≥99 wt. %.

Examples of Configurations for Heat Soaking Cracked Tar Solids

FIG. 1 is a diagram illustrating an apparatus for carrying out certainaspects of the invention. More generally, a configuration similar toFIG. 1 can be used for heat soaking a higher-density portion of apyrolysis tar composition.

In FIG. 1, a steam cracker effluent 102 comprising SCT is introduced tofirst thermal treatment stage 124, e.g., the bottoms section of a tarknock-out drum. A primarily vapor-phase stream is conducted away fromstage 124 via line 128 to primary fractionator 126 for separation of atleast a quench oil stream 160 and a process gas 170. An SCT compositioncomprising thermally-treated (e.g., heat-soaked) SCT is conducted awayfrom stage 124 via line 105.

A recycle stream 104 and an optional stream 103 (comprising an optionalfirst utility fluid and/or an optional first separation fluid providedby a source (not shown)) are added to the SCT composition to produce atar-fluid mixture. The tar-fluid mixture is introduced to a first SCTseparation stage 120, which typically includes at least one centrifuge,such as a decanter centrifuge. A first higher-density portion (conductedaway via line 125) and a first lower-density portion (conducted away vialine 122) are separated from the tar-fluid mixture in stage 120. Incontinuous operation, the first higher-density portion conducted vialine 125 typically comprises ≥50 wt. % of first higher-density portionavailable for further processing in heat soak vessel 116, e.g., ≥75 wt.%, such as ≥90 wt. %.

In the configuration shown in FIG. 1, at least a portion of the firstlower-density portion is conducted via line 122 to an optional stage 140hydroprocessing, e.g., SATC hydroprocessing. The first higher-densityportion can be passed to one or more optional stages, e.g., at least oneoptional size reduction stage 130, to produce a comminuted firsthigher-density portion. The first higher-density portion is combinedwith diluent (comprising a second utility fluid and/or second separationfluid provided by one or more sources (not shown)) via lines 127 and/or135, e.g., before and/or after the comminuting. The diluted firsthigher-density portion via line 114 is introduced to second thermaltreatment stage 116 (e.g., a second heat soak vessel). Second thermaltreatment stage 116 provides a thermally-treated first higher-densityportion which is introduced via line 118 to second SCT separation stage150, which typically includes at least one centrifuge, such as adecanter centrifuge. Stage 150 provides a second higher-density portionwhich can be sent away via line 122, such as for storage, additionalthermal treatments, and/or additional separations. A secondlower-density portion is recycled via line 104.

Examples High Temperature Dissolution/Decomposition Exemplification ofthe Second Thermal Treatment.

0.5 g of solids obtained from a representative tar (in this case arepresentative SCT) is mixed with approx. 50 mL toluene in a bombreactor. The toluene corresponds to the second utility fluid of line127. The mixture is thermally-treated (heat soaked) at a temperature ina range of from 250° C.-350° C. (sand bath temperature) for 30 minsunder 500 psig N₂. The reactor was quenched quickly with cold water, andfiltered through a 1.5 um filter. The reactor was washed with excesstoluene to ensure complete solids recovery. The weight of remainingsolids is measured after the thermal treatment, and solids loss wt. % isreported.

FIG. 2 is a graph illustrating the amount of solids loss (wt. %) as afunction of the temperature applied in the process, using toluene as asolvent. The experimental results indicate that at least 80% or more ofthe solids (a relatively low-value material) can be upgraded to ahigher-value liquid-phase material that is suitable for use as a SATCFeed. Accordingly, the key operating parameters include temperature,residence time, and a suitable solvent. It is observed that 30 minutesto 60 minutes of heat soaking, at a temperature of 275° C.-300° C. issufficient.

All documents described herein are incorporated by reference herein forpurposes of all jurisdictions where such practice is allowed, includingany priority documents and/or testing procedures to the extent they arenot inconsistent with this text, provided however that any prioritydocument not named in the initially filed application or filingdocuments is not incorporated by reference herein. Although forms ofembodiments have been illustrated and described, various modificationscan be made without departing from the spirit and scope of the presentdisclosure. Accordingly, it is not intended that the present disclosurebe limited thereby. Likewise, the term “comprising” is consideredsynonymous with the terms “including” and “containing” Likewise whenevera composition, an element or a group of elements is preceded with thetransitional phrase “comprising,” it is understood that we alsocontemplate the same composition or group of elements with transitionalphrases “consisting essentially of,” “consisting of,” “selected from thegroup of consisting of,” or “is” preceding the recitation of thecomposition, element, or elements and vice versa.

Certain embodiments and features have been described using a set ofnumerical upper limits and a set of numerical lower limits. It should beappreciated that ranges including the combination of any two values,e.g., the combination of any lower value with any upper value, thecombination of any two lower values, and/or the combination of any twoupper values are contemplated unless otherwise indicated. Certain lowerlimits, upper limits and ranges appear in one or more claims below.

1. A tar upgrading process, comprising: thermally-treating a tar in afirst thermal treatment to produce a tar composition; separating from atleast a portion of the tar composition a first lower-density portion anda first higher-density portion, wherein the first higher density portioncomprises solids in an amount A₁ wt. % based on the weight of the firsthigher density portion; conducting away an upgraded pyrolysis tarcomposition comprising at least a portion of the first lower-densityportion; thermally-treating at least a portion of the firsthigher-density portion in a second thermal treatment to form athermally-treated first higher-density portion, wherein (i) thethermally-treated first higher density portion comprises solids in anamount A₂ wt. % based on the weight of thermally-treated first higherdensity portion and (ii) A₂<A₁; separating from at least a portion ofthe thermally-treated first higher-density portion a secondlower-density portion and second higher-density portion; and adding atleast a portion of the second lower-density portion to one or more of(i) the pyrolysis tar before and/or during the first thermal treatment,(ii) the pyrolysis tar composition, (iii) the first higher-densityportion, and (iv) the first lower-density portion.
 2. The process ofclaim 1, further comprising adding a fluid to the tar composition,wherein ≥90 wt. % of the added fluid is transferred to the firstlower-density portion.
 3. The process of claim 1, further comprisingadding a diluent to the first higher-density portion, and wherein ≥90wt. % of the added diluent resides in the second lower-density portion.4. The process of claim 1, wherein the first thermal treatment includesmaintaining the tar at a temperature ≤350° C. for a time in the range offrom 10 minutes to 60 minutes.
 5. The process of claim 1, wherein thefirst thermal treatment includes maintaining the tar at a temperature inthe in the range of from 150° C. to 300° C. for a time in the range offrom 15 minutes to 30 minutes.
 6. The process of claim 1, wherein (i)the second thermal treatment includes maintaining the firsthigher-density portion at a temperature in the range of from 220° C. to500° C. for a time in the range of from 10 minutes to 100 minutes and(ii) A₂≤0.8*A₁.
 7. The process of claim 1, wherein the second thermaltreatment includes maintaining the first higher-density portion at atemperature in the range of from 250° C. to 400° C. for a time in therange of from 20 minutes to 90 minutes.
 8. The process of claim 1,wherein A₂ is in the range of from 10% of A₁ to 40% of A₁.
 9. Theprocess of claim 1, wherein the tar is a pyrolysis tar comprising steamcracker tar.
 10. The process of claim 1, wherein the tar is a steamcracker tar produced by steam cracking a steam cracker feed thatincludes ≥10 wt. % based on the weight of the steam cracker feed ofmaterial that is solid-phase or liquid-phase at 25° C. and a pressure of1 bar absolute.
 11. The process of claim 1, wherein: (i) the tar is asteam cracking tar produced by steam cracking a hydrocarbon feedcomprising ≥1 wt. % of hydrocarbon having a normal boiling point ≥566°C. based on the weight of the steam cracker feed; (ii) the streamcracker includes a convection section and a radiant section; (iii) thehydrocarbon feed is preheated in the convection section and combinedwith steam to produce a steam cracker feed; (iv) a primarily vapor-phasestream and a primarily non-vapor-phase stream are separated from atleast a portion of the steam cracker feed, wherein ≥50 wt. % of anyhydrocarbon having a normal boiling point ≥566° C. in thehydrocarbon-containing feed is transferred to the non-vapor-phasestream; (v) at least a portion of the primarily vapor-phase stream isconducted into an inlet of at least one radiant coil located in theradiant section for cracking under steam cracking conditions, whereinthe radiant coil includes the inlet and an outlet, and the steamcracking conditions include: a temperature at the radiant coil outlet inthe range of from about 760° C. to about 1200° C., a steam crackingpressure at the radiant coil outlet in the range of from about 1bar(absolute) to about 10 bar(absolute), and a steam cracking residencetime in the radiant coil in the range of from about 0.1 seconds to about2 seconds; (vi) a steam cracker effluent is conducted away from theradiant section; and (vii) separating at least the steam cracker tarfrom the steam cracker effluent.
 12. The process of claim 11, whereinthe primarily vapor-phase stream and the primarily non-vapor-phasestream are separated from the steam cracker feed in a separation stageintegrated with the convection section, and wherein the separatedprimarily vapor-phase stream is exposed to additional heating in theconvection section before the cracking.
 13. The process of claim 11,wherein the temperature at the radiant coil outlet is in the range offrom about 880° C. to about 1,200° C.
 14. The process of claim 11,wherein the temperature at the radiant coil outlet in in the range offrom about 1,000° C. to about 1,200° C., and the steam cracking pressureis in the range of from about 6 bar(absolute) to about 10bars(absolute).
 15. The process of claim 11 wherein the steam crackingtemperature is in the range of from about 760° C. to about 880° C., andthe steam cracking pressure is in the range of from about 1bar(absolute) to about 5 bars(absolute).
 16. The process of claim 1,wherein the tar composition further comprises material resulting fromthe first thermal treatment.
 17. The process of claim 3, furthercomprising grinding the first higher-density portion before and/or afteradding the diluent.
 18. A steam cracker tar upgrading processcomprising: steam cracking a hydrocarbon feed comprising heavy oil toform a steam cracker effluent comprising steam cracker tar; separatingat least a portion of the steam cracker tar from the steam crackereffluent; thermally treating at least the separated steam cracker tar ina first thermal treatment to produce a steam cracker tar composition;adding a first utility fluid and/or a first separation fluid to thesteam cracker tar composition to produce a tar-fluid mixture; separatingfrom the tar-fluid mixture (i) a first lower-density portion comprisingupgraded steam cracker tar and (ii) a first higher-density portion;conducting away at least a portion of the first lower-density portion;introducing a second utility fluid to the first higher-density portionto form a diluted first higher-density portion, wherein the dilutedfirst higher density portion comprises solids in an amount A₁ wt. %based on the weight of the first higher density portion;thermally-treating the diluted first higher-density portion in a secondthermal treatment to form a thermally-treated first higher-densityportion, wherein (i) the thermally-treated first higher density portioncomprises solids in an amount A₂ wt. % based on the weight ofthermally-treated first higher density portion and (ii) A₂≤0.8*A₁;separating in a second separation at least a second lower-densityportion and a second higher-density portion from the thermally-treatedfirst higher-density portion; and adding at least a portion of thesecond lower-density portion to one or more of (i) the steam crackereffluent, (ii) the steam cracker tar before and/or during the firstthermal treatment, (iii) the steam cracker tar composition, (iv) thetar-fluid mixture before and/or during the separation of the firsthigher-density portion and the first lower-density portion, (v) thefirst higher-density portion, and (vi) the first lower-density portion.19. The process of claim 18, wherein (i) steam cracking the heavy oil isperformed at a temperature of from about 760° C. to about 880° C., apressure of from about 1 bar(absolute) to about 5 bars(absolute), and aresidence time of from about 0.1 seconds to about 2 seconds; (ii) thefirst thermal treatment includes maintaining the steam cracker tar at atemperature in the in the range of from 150° C. to 300° C. for a time inthe range of from 15 minutes to 30 minutes; and (iii) the second thermaltreatment includes maintaining the diluted first higher-density portionat a temperature in the range of from 300° C. to 400° C. for a time inthe range of from 30 minutes to 60 minutes.
 20. The process of claim 18,the tar-fluid mixture comprises the steam cracker tar composition in anamount in the range of about 40 wt. % to about 80 wt. % of, based on theweight of the tar-fluid mixture.
 21. The process of claim 18, furthercomprising grinding the first higher-density portion before and/or afterintroducing the second utility fluid.
 22. The process of claim 18,further comprising (i) hydroprocessing at least a portion of the firstlower-density portion and (ii) conducting away at least a portion of thesecond higher-density portion.
 23. The process of claim 18, wherein (i)the first and/or second thermal treatments include heat soaking in atleast one soaker drum, and/or (ii) the first and/or second separationsinclude centrifuging and/or filtration.
 24. A steam cracker tarupgrading process comprising: steam cracking a hydrocarbon feedcomprising heavy oil at a temperature of from about 760° C. to about880° C., a pressure of from about 1 bar(absolute) to about 5bars(absolute), and a residence time of from about 0.1 seconds to about2 seconds to form a steam cracker effluent comprising a steam crackertar; separating at least a portion of the steam cracker tar from thesteam cracker effluent; thermally treating at least the separated steamcracker tar in a first thermal treatment by maintaining the steamcracker tar at a temperature of from 150° C. to 300° C. for a time offrom 15 minutes to 30 minutes to produce a steam cracker tar compositioncomprising polymeric particulates formed during or as a result of thefirst thermal treatment; adding a first utility fluid and/or a firstseparation fluid to the steam cracker tar composition to produce atar-fluid mixture; separating from the tar-fluid mixture (i) a firstlower-density portion comprising upgraded steam cracker tar and (ii) afirst higher-density portion comprising the polymeric particulates,wherein the first higher density portion comprises the polymericparticulates in an amount A₁ wt. % based on the weight of the firsthigher density portion; conducting away at least a portion of the firstlower-density portion; introducing a second utility fluid to the firsthigher-density portion to form a diluted first higher-density portion;thermally-treating the diluted first higher-density portion in a secondthermal treatment by maintaining the diluted first higher-densityportion at a temperature in the range of from 300° C. to 400° C. for atime in the range of from 30 minutes to 60 minutes to form athermally-treated first higher density portion wherein (i) thethermally-treated first higher density portion comprises conversionproducts of lesser density as compared to the polymeric particulates,(ii) the thermally-treated first higher density portion comprisespolymeric particulates in an amount A₂ wt. % based on the weight ofthermally-treated first higher density portion and (iii) A₂≤0.8*A₁;separating in a second separation at least a second lower-densityportion and a second higher-density portion from the thermally-treatedfirst higher-density portion, the second lower-density portioncomprising the conversion products of lesser density; and adding atleast a portion of the second lower-density portion to one or more of(i) the steam cracker effluent, (ii) the steam cracker tar before and/orduring the first thermal treatment, (iii) the steam cracker tarcomposition, (iv) the tar-fluid mixture before and/or during theseparation of the first higher-density portion and the firstlower-density portion, (v) the first higher-density portion, and (vi)the first lower-density portion. 25.-30. (canceled)